Increase MAX_PATCH_PLANES

Some custom maps apparently need a larger value for MAX_PATCH_PLANES.
These snuck under the limit with original Q3 due to the vagaries of
floating point error/modern compilers/fastmath etc.. See issue #186.

code/qcommon/cm_patch.h

@@ -61,7 +61,7 @@ properly.
 
 
 #define	MAX_FACETS			1024
-#define	MAX_PATCH_PLANES	2048
+#define	MAX_PATCH_PLANES	4096
 
 typedef struct {
 	float	plane[4];