Polyobject collide fix

See merge request STJr/SRB2Internal!288

This reverts commit 749c2753.

After looking at the FOF part of P_LineOpening for a while I now realise many of these variables aren't even necessary, so I removed them all.

(Naturally I did the same to the camera equivalent)

Edit a lot of the rest of the polyobject-related code in P_LineOpening to make more sense and be more optimised.

* If you collide with a line belonging to a polyobject, you should NEVER have to care about any FOFs that might be present in either sector of the linedef. This could lead to colliding with ghostly FOFs that aren't actually there or something dumb, if someone decided to give either of the polyobject's control sectors FOFs for some reason. We don't want that, obviously.
* Polyobjects without POF_CLIPPLANE apparently are supposed to have a top and bottom "physical" height of value INT32_MAX and _MIN respectively, according to P_CheckPosition ...let's be consistent with this.
* Finally, there is no more need for that back = front nonsense hack anymore with my changes made.

P_LineOpening: set int32 max/min as defaults for opentop, openbottom etc if a linedef you touched belongs to a polyobjetc. the only thing that really matters in this scenario is the polyobject itself after all!

(This is an untested fix for VAda's apparent collision with thin air below a polyobject in ACZ2 in beta 5)

Fang fixes

Closes #154 and #140

See merge request STJr/SRB2Internal!285

Build fixes

See merge request STJr/SRB2Internal!287

Use strtok instead of strtok_r

See merge request STJr/SRB2Internal!286

This fixes Fang's bounce on slopes and doesn't seem to make a difference otherwise, but there's still a non-zero chance this broke something.

(MI said I could commit to master since it was only a single line.)

Revert "Revert MusicPlus"

See merge request STJr/SRB2Internal!282

New ring sparkles

See merge request STJr/SRB2Internal!271

Quick state fixes

See merge request STJr/SRB2Internal!283

* Fix the thing where you don't go through super transformation frames when starting NiGHTS.

This reverts commit 99dbcb9f.

This reverts commit 603d5805.

Revert musicplus (for now)

See merge request STJr/SRB2Internal!281