Add more test coverage for RGBASM (#1256)

This also fixes two bugs: `-1 >>> 32` was -1 not 0, and `macro_FreeArgs` should have been called but wasn't.

include/asm/charmap.hpp

@@ -9,7 +9,6 @@
 #define DEFAULT_CHARMAP_NAME "main"
 
 struct Charmap *charmap_New(char const *name, char const *baseName);
-void charmap_Delete(struct Charmap *charmap);
 void charmap_Set(char const *name);
 void charmap_Push(void);
 void charmap_Pop(void);