Set up build environment for building with SDL2
Remove dedicated console and move some platform detection code to SDL
Move system timing over to SDL2
Move shared library loading over to SDL2
Merge in changes from aborted Sixense branch
-Moved Xinput and Joystick code paths out of in_win.c (modularity will help with SDL2 porting)
-Fixed issues with number of key events being hardcoded
-Increased max num of key events (256->512)
-Added SCR_CenterAlert function that prints a message on screen without spamming console
SDL2 window creation works - but is missing many features
Fixes / Updates
-Fix for keyboard events not firing right
-Fix mouse button handling
-Remove winMain in favor of SDL main
-Add some _WIN32 specific defines
-Update libjpeg to version 8
-Build against multithreaded DLL libraries
-Fixed issue prevent xinput code path from working
-Moved swap interval to SDL
-Fixed for gamma
Fixes for build environment
SDL2 related cleanup and fixes
-No longer directly set gamma ramp (use SDL2_SetWindowBrightness instead)
-Fix issue with window not being visible after mode change
-Restore alt-enter to toggle fullscreen
-Restore ability to set window position correctly
Restore original video mode setting behavior
Clean up interface between renderer and GL implementation
Rename r_width and r_height to vid_width and vid_height
Fix issues with gamma adjustment when changing window position
Initial port of mouse handling to SDL2
Bug fixes

-Fix broken caustics
-Restore r_bitdepth
-Restore broken lightmap scaling when hardware gamma is disabled
-Fix broken particles
Fix mouse wheel
Remove cruft associated with stereo 3D glasses

-This was a partially implemented feature from KMQuake 2
Restore setting refresh rate

-Also renamed r_displayrefresh to vid_refresh
Move to SDL2 audio backend

Fix crashing
Update sound menu

-Remove buffer selection option
-Add audio driver option