-Work In Progress: add SDL 2 support for input system and libtextscreen.
-Remove mouse_driver CVAR. SDL 2 provides raw mouse input for Windows users.

git-svn-id: http://odamex.net/svn/root/branches/sdl20@4606 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Add i_sdl.h to act as a wrapper for SDL.h and provide a few simple macros for compile-time version identification.

git-svn-id: http://odamex.net/svn/root/branches/sdl20@4607 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Update the CodeBlocks project file for i_sdl.h

git-svn-id: http://odamex.net/svn/root/branches/sdl20@4608 b0bcef46-2027-0410-bd56-ab726e9a1d04