Moved the handling of P_PlayerInSpecialSector to P_PlayerAfterThink from P_PlayerThink.
* This allows the player to get hurt on sloped lava surfaces that are moving downwards.
* Also prevents the player from standing on death pits for 1 tic.
* Prevents the player moving 1 extra tic's worth of movement of pain when hit by sector.
* Thankfully, no consequences re conveyors.
* Like, the only consequences I've found have been positive. However, this DOES need to be thoroughly investigated before it can be allowed anywhere near Next itself.

Fixed a bug with being able to go under the lava because P_CheckSolidLava doesn't take slopes into account.

(neither does P_CanRunOnWater, but I don't think it's necessary to make that check more complicated as you probably shouldn't be able to waterrun up steep surfaces anyways)

Forcing on triggerspecial_touch for slopes, because pain slopes and it would be a pain to handle this manually.

A bunch of fixes that allow for proper handling of triggerspecial_touch. Not perfect, but I don't have any more time to spend tonight.

Prevent resampling-related crashes on Linux 64-bit

P_IsPointInSubsector fix! (Most importantly: Knuckles No Longer In Space)

Now works in GL by not relying on stuff which GL mutates! Thanks for the guidance, @MonsterIestyn! Tested in Steel_Titanium's Nightlight Ruins (in SUGOI), which had the perfect testbed for plenty of Knuckles issues AND is one of the first maps out to the public which eschews thok barriers altogether in some sections.

* Knuckles climbing on one sided lines is now super great and doesn't allow any space-climbing at all, OGL-exclusive OR renderer-independent. I was able to restore my earlier perfect-in-Software fix because now it also works fine in GL, too!
* The devmode TELEPORT command now actually prevents you from going outside maps which don't have thok barriers near where you were. (It only prevented you from going outside maps with thok barriers because the thok barriers bled outwards and failed some other conditions.)
* Camera now behaves identically between Software and GL. (Look closely at p_user.c - I didn't modify any code in that section, but the chasecam DOES call P_IsPointInSubsector...)
* Here's a biggun - OpenGL precipitation is ALSO fixed! Yup. That's right. It used P_IsPointInSubsector too, and THAT'S why it was broken for all this time. (I did have to do a few other changes beyond just flipping the ifdef, but HOLY SHIT.) Tested this in Mystic Realm's second zone, which kept rain all the way through in OGL!!

(And yes, I AM compiling with OGL on for this branch.)

See merge request !128

YUP, I just fixed OGL Precipitation with this branch too. What the fuck? Squashing ancient bugs, woo.

P_IsPointInSubsector now works in both Software and GL, which means it can be used as the main driver behind support for Knuckles climbing on one-sided walls.

Also, the "teleport" devmode command can now gracefully handle coordinates specified outside maps with no/few thok barriers, which previously prevented teleport via the thok barrier bleed's sector floor and ceiling being equal.

Fixing various problems with MF_SOLID collision

(I, toast, wrote the original merge request, but Alam made this merge request because I made a mistake. Twice. In a row.)

* Solid objects are now no longer intangible when your z is less than the other object's.
    * I originally thought the bug was limited to just solid objects on slopes (hence the branch name), and was wondering about undesired side effects - but looking at this gfy, this was a major bug that slopes made easier to expose.
    * Unfixed = http://gfycat.com/BareLimitedCavy
    * Fixed = http://gfycat.com/JubilantOffensiveGar
* You now properly lose your momentum when jumping at a solid object.
    * The way I fixed this was a hack, but it was originally a much worse hack which resulted in very bizzare physics issues, so...
    * Unfixed = http://gfycat.com/ShockingAbsoluteArthropods (also demonstrates the first bug)
    * Fixed = http://gfycat.com/EmbellishedCourageousGordonsetter

See merge request !119

Fixed players disappearing when spindashing whilst wearing multi-layer shields

* Before: http://i.imgur.com/gxUFElo.png
* After: http://i.imgur.com/NxsOg94.png

The problem was that MT_OVERLAY's default radius and height were never getting changed from 1*FRACUNIT, and that meant that when you spindashed, the game considered it completely below the surface of the flat you were standing on. Since you're not usually clipped on flats that don't belong to FOFs, we didn't notice this aspect of the issue sooner.

(SORRY FOR THE MULTIPLE MR'S AGAIN I TOTALLY SUCK AT REMEMBERING TO MAKE SURE IT GOES TO NEXT INSTEAD OF MASTER)

See merge request !124

Fix ANIMDEFS process order

v.drawScaled negative scales fix

Lua now errors if you try to use negative scales with v.drawScaled, rather than crashing as it does in 2.1.16 currently. Not much else to say here.

See merge request !126

Not in P_SetupLevel. That's just dumb.

ANIMATED and ANIMDEFS are now processed in reverse order,
and duplicate definitions in ANIMDEFS are dropped.

Fixing FF_REVERSEPLATFORM clipping fixes

Forgot the case where == 0.

Tested by @wolfy852 in Top Down, where the bugs this caused were first discovered.

See merge request !121

Even more slope-related fixes

What it says on the tin pretty much:

Currently included fixes:
* Pusher specials applied to FOFs did not properly account for slopes applied to the bottom plane; this probably was just a minor slipup that appeared on adding the support in the first place, I take it? (some waterfall in the last section of SUGOI's Fudge Canyon is the only place I can think of offhand where this bug is noticable)

See merge request !114

Treating " as whitespace in TEXTURES (and animdefs too i guess)

SLADE adds this character in its TEXTURES editor and makes SRB2 cry unless the lump is manually edited; this just treats it as whitespace so we don't have to think too hard about it.

Also, two I_Errors now refer to the correct lump name.

See merge request !122

Fixed that really annoying bug where you disappear when spindashing on top of a FOF whilst wearing a multi-layer shield.

(the problem was that MT_OVERLAY's default radius and height were never getting changed from 1*FRACUNIT, and that meant that when you spindashed, the game considered it completely below the surface of the flat you were standing on. Since you're not usually clipped on flats that don't belong to FOFs, we didn't notice this issue sooner.)

Fix demo recording in Linux

Fixed the problem with the reverseplatform_clipping branch that caused springs to fall through platforms, as tested by Wolfs in TD.

Prevent overflow when attempting to calculate the space between floor and ceiling. (I didn't notice any bugs as a result of the previous behvaiour, but you never know.)

Fixed the thing where if you thok into a solid object you spin really fast in the air without moving OR losing your momentum.

HOWEVER, since these changes to PIT_CheckThing do raise questions about whether there may be unintended side effects here. As a result, I may remake this for internal only if necessary.