- transitioned project to CMake and deleted most of the old build system.

The EDuke32 and RedNukem frontends are working, Blood isn't yet.

Notes:

many of the CMake variables and its output still refer to zdoom. Before changing that I wanted to make sure to be able to commit something that works.
support code for Windows XP has been entirely removed. On Windows this will only target Vista and up.
the crc32.h header had to be renamed to deconflict from zlib.
several Windows API calls were changed to call the A-versions directly. Weirdly enough there were places that defined their parameters as T types but in a non-working way.
removed some remaining editor files and support for the native software rendering only Windows backend.
in a few simple cases, replaced 'char' with 'uint8_t'. The code as-is depends on chars being unsigned which is non-portable. This needs to be carefully reviewed.

source/build/src/polymost.cpp

@@ -6784,7 +6784,7 @@ EDUKE32_STATIC_ASSERT((int)RS_YFLIP == (int)HUDFLAG_FLIPPED);
 //cx1,...     clip window (actual screen coords)
 
 void polymost_dorotatespritemodel(int32_t sx, int32_t sy, int32_t z, int16_t a, int16_t picnum,
-    int8_t dashade, char dapalnum, int32_t dastat, uint8_t daalpha, uint8_t dablend, int32_t uniqid)
+    int8_t dashade, uint8_t dapalnum, int32_t dastat, uint8_t daalpha, uint8_t dablend, int32_t uniqid)
 {
     float d, cosang, sinang, cosang2, sinang2;
     float m[4][4];
@@ -7022,7 +7022,7 @@ void polymost_dorotatespritemodel(int32_t sx, int32_t sy, int32_t z, int16_t a,
 }
 
 void polymost_dorotatesprite(int32_t sx, int32_t sy, int32_t z, int16_t a, int16_t picnum,
-                             int8_t dashade, char dapalnum, int32_t dastat, uint8_t daalpha, uint8_t dablend,
+                             int8_t dashade, uint8_t dapalnum, int32_t dastat, uint8_t daalpha, uint8_t dablend,
                              int32_t cx1, int32_t cy1, int32_t cx2, int32_t cy2, int32_t uniqid)
 {
     if (usemodels && tile2model[picnum].hudmem[(dastat&4)>>2])