Remove assembly files.
Change R_Draw(|TL)Column from a function pointer to a function.
Start to flesh out video for the xCORE.
Avoid use of SDL outside the system specific files.
Implement I_GetTime_RealTime on xCORE, some other fixes

With this change DOOM is now showing signs of life.
Rename file, no functionality change.
Add a new file for xCORE system helper functions.
Reduce memory size to 16MB, enable inlining.
Add all target.