GFZ3 Unfuckening

Some tweaks to the GFZ3 Eggmobile's behaviour to make it less frustrating for old and new players alike.

* GFZ3 Eggmobile's laser won't change its angle when you move left and right anymore.
    * Changed because its ability to move quickly was extremely punishing for new players (see ProJared's youtube video on the matter).
    * http://gfycat.com/PassionateUnknownAgama (the twitching on the third laser has been fixed since this was recorded)
* GFZ3 Eggmobile will, when too far away from the ground and moving upwards, slow itself down vertically.
    * This was punishing and annoying for both old and new players alike.
    * http://gfycat.com/CornyLeftDungbeetle (old values - the typical settling height is slightly lower now)

See merge request !42

No more double-decker Detons

Oversight of a tiny hack when working on the flickies branch meant detons released twin flickies when hitting stuff. As cute as that is, it's also pretty weird.

See merge request !62

# Conflicts:
#	src/d_clisrv.c
#	src/doomdef.h
#	src/p_map.c

A spike bug no more

Jumping at spikes on FOFs in reverse gravity - most notably in ERZ3 - no longer teleports you downwards into the death pit beneath it.

See merge request !157

Fixed a stupid bug involving jumping at spikes on FOFs in reverse gravity caused by my own incompetence/assumptions.

(I COULD have hacked around the hack, but when a line tells you it's a hack and it makes things work by removing it, you remove it.)

This reverts commit 6476cf3c, reversing
changes made to 0186b90b.

Appveyor: compile with Mingw32 GCC 4.9.3

Let use an old GCC to compile SRB2

See merge request !112

Last few changes for 2.1.17

what it says on the tin

* Updated version number
* Added LJSonic to credits (and changed how I look in the credits to be less stupid)
* fixed resynching players seeing the host turn into a spectator for no reason

See merge request !155

Otherwise we can't force updates!

Netcode shit

Lua additions

Thought I'd may as well make a merge request so I can remind people of all the various Lua-related changes here (and because it's about time some of them got in):

* Added `P_PointOnLineSide(x, y, line)`. Allows you to quickly determine which side of a line faces the point. *line* can be a real line_t or a custom defined line (just like with P_ClosestPointOnLine).
* Added seg_t and node_t support to Lua (note: these are disabled for now, due to complications with OpenGL that we all know something of by now. Bit of a shame really :( ) - of note is node.children and node.bbox:
 * node.children[] is an array that takes 0 or 1 as indexes (or "right" and "left", alternatively)
 * node.bbox(child,bboxcoord) is a two-arg function: child can be 0 or 1 (or "right" and "left", alternatively), bbox coord can be 0,1,2 or 3 (or "top", "bottom", "left" and "right", alternatively)
 * aside from the above, segs[] and nodes[] store the segs/nodes of the current map; segs.iterate and nodes.iterate iterates through segs/nodes
 * NF_SUBSECTOR is also available for usage with node.children
* You can now get the palette indexes (i.e. colormap[n]) of colormap userdata from `v.getColormap`, where n is a palette index number between 0 and 255. Useful for finding out which palette colors turned into what, if they changed at all
* ffloor_t userdata can now save to and be read from $$$.sav in netgames properly; this means custom mobj/player variables and NetVars can both send/recieve them directly if you wanted
* **IMPORTANT** Blockmap search library! (with a new file: lua_blockmaplib.c)
 * Format of iteration function: `searchBlockmap(searchtype, function, mobj, [x1, x2, y1, y2])`. Returns true if search was uninteruppted, false if the iteration function returned true at any point
 * *searchtype* can be either "objects" or "lines", for looking for mobj_t and line_t stuff in the blockmap respectively
 * *function* is a function of your choice to iterate with: (sorry I can't get the next two bullets to be one indent further to the side)
   - format of function needed: `funcname(mobj, foundmobj)` or `funcname(mobj, foundline)` (for searching for objects and lines, respectively)
   - return value of *function* affects searching somewhat: nil doesn't change searching, false ends searching in a block (but doesn't stop searching, it just moves onto the next), and true ends the full search. Both returning true or false ultimately makes `searchBlockmap` return false.
 * *mobj* is the reference mobj that you're checking around (if you don't supply x/y ranges to search in, it defaults to checking within the mobj's radius in both axes). If *mobj* was removed mid-search the search stops and `searchBlockmap` returns false
 * (optional) *x1, x2, y1, y2* are coordinates on the map to search the blockmap between, if given

See merge request !54

*takes the cookie*

-Added a timeout for game state downloading to prevent definitive join freezes in some cases. The timeout has a minimum value of "jointimeout" and gets higher as the game state grows in size
-If the server tries to kick a joiner who is downloading the game state, they will get a timeout instead, because a regular kick would only happen once the game state has been downloaded
-Added a timeout for player ticcmd packets, again to prevent freezes to happen in some cases
-File/game state downloading is now faster, the speed is controlled by the "downloadspeed" cvar, in packets per tic
-The reason is now properly shown when the server refuses connection
-Changed the default values of "nettimeout" to 10 seconds (previously 15) and "maxsend" to 4 MB (previously 1)
-Added a "noticedownload" cvar that displays a message in the server console when someone is downloading a file

CMake: Fix nasm Linux builds

When compiling under Linux with CMake and nasm/yasm enabled, the operation would fail during linking with undefined symbols related to the tmap files.
This commit adds support for passing flags to the assembler and passes ```-DLINUX``` in order to compile.

After this change, binaries are successfully compiled with either nasm or yasm on Linux systems.
Tested on Ubuntu.

See merge request !153

Added transmaps to non modifying lump list.

CMake: split inline ASM code from vid_copy.s code

See merge request !151