Fix for rendering sprites in skyboxes
This branch fixes the visual glitches one sees with sprites for objects within skyboxes, typically with parts of or all of some sprites disappearing from view even though they shouldn't be.
See merge request !84
Behaves ALMOST as you'd expect. It gets the z position of the slope at the player coordinates when it comes to the sectorlist check (which is first), though, so there's a few oddities that are amplified with steep slopes:
* If the slope's sloping away from you at a steep angle, you might not be able to step down onto it, but you won't teeter (because it's at a step-down-able height if it extended to directly beneath you)
* If the slope's sloping towards you at a steep angle, you might end up in teetering frames when you're able to step down onto it (because it's NOT at a step-down-able height if it extended to directly beneath you)
HOWEVER, it would be pretty obnoxious to hold back code which is functionally superior in every way otherwise, and it doesn't really seem like there's a good way to get that checked tbph
Also updated any relevant project files that I can think of to include the new files, as well as the makefile of course. Some of the other project files haven't been touched in years so I'll leave those alone ...unless someone objects
OpenGL slope fixes again
This branch just adds the relevant code for OpenGL to properly check slopes regarding "closed door" segs (those between two sectors that cannot be crossed normally) and "window" segs (those between two sectors of differing plane heights that you CAN cross, which would probably display top or bottom textures), so you don't get HOMs when the the slopes create a closed door even though the normal sector heights wouldn't or something.
(if you couldn't understand that, my slopes test map shows what I mean to the right of the player start: https://dl.dropboxusercontent.com/u/25409000/2.1/mi-slopetest.wad)
See merge request !81
Basically this makes sure numwadfiles is updated before loading the SOC/Lua scripts, so if a Lua script calls COM_BufInsertText with the contents "addfile scr_mysticrealm.wad" it can't overwrite the last written wadfile slot! Not that COM_BufInsertText really should be used like that to begin with
*Didn't take into account object scale
*Doubled force when on the ground (ignore what the comment of the line I moved says, it was relevant for slopes...)
This also led to a mistake with slopes, where I was double-multiplying by the gravity constant to get half (because of a quirk of numbers...)