C only version

[jherrera80]

Would it be possible to add an option in the makefile to compile PCDoom v2 as C only, without any assembly? That way only Open Watcom would be needed and not tasm, as in PCDoom v1.

This would mean no joystick support and C versions of R_DrawColumn and R_DrawSpan (the ones from v1) surrounded by "#ifdef C_ONLY" when compiling with pure C, and probably adding back m_fixed.c.

Thanks.