Added rect draw api

Added some new maths types
Updated shaders to use new D_Rect structure
Added rect buffers to frames
Misc cleanup

code/core/macros.h

@@ -4,6 +4,7 @@
 #include <assert.h>
 
 #define Assert(exp) assert(exp)
+#define StaticAssert(exp) static_assert(exp, #exp)
 
 #define ArraySize(x) (sizeof(x) / sizeof((x)[0]))
 #define Min(a, b) ((a) < (b) ? (a) : (b))