Software crashes fix
This branch SHOULD fix the many crashes people have reported lately that all point to the software renderer. Simply put, the software renderer allowed stuff to be drawn out of the screen even though that wasn't safe, and even the existing checks to prevent that didn't work.
If you saw me worrying about the sky HOMs I discovered in AGZ earlier in the commits for this branch, don't worry - it turns out that issue already existed in 2.1.15's srb2win.exe (and probably srb2dd.exe too) anyway, the changes in this branch didn't cause them. Hopefully nothing else broke then.
See merge request !75
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
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
