- Changed compilation for g_doom, g_heretic, g_hexen and g_strife folders

so that all files are included by a central one instead of compiling 
  each one separately. This speeds up the compilation process by 25%
  when doing a complete rebuild in Visual C.
- Cleaned up more header dependencies.

SVN r1226 (trunk)

src/r_data.cpp

@@ -43,6 +43,9 @@
 #include "v_text.h"
 #include "st_start.h"
 #include "doomstat.h"
+#include "r_bsp.h"
+#include "r_segs.h"
+#include "v_palette.h"
 
 
 static int R_CountGroup (const char *start, const char *end);