- 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/g_shared/sbarinfo_display.cpp

@@ -55,6 +55,7 @@
 #include "a_weaponpiece.h"
 #include "a_strifeglobal.h"
 #include "g_level.h"
+#include "v_palette.h"
 
 static FRandom pr_chainwiggle; //use the same method of chain wiggling as heretic.