Use inttypes for stdint types

This should help make RGBDS portable to systems with 16-bit integers,
like DOS.

For kicks, use the macros for 16-bit and 8-bit integers.

Fix other miscellaneous things, like #include ordering and other
printf-format related things.

Reduce repitition in math.c while I'm there.

src/asm/asmy.y

@@ -9,6 +9,7 @@
 %{
 #include <ctype.h>
 #include <errno.h>
+#include <inttypes.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -79,7 +80,7 @@ size_t symvaluetostring(char *dest, size_t maxLength, char *symName,
 			strncpy(dest, write_ptr, maxLength + 1);
 		} else {
 			fullLength = snprintf(dest, maxLength + 1,
-							  mode ? mode : "$%X",
+							  mode ? mode : "$%" PRIX32,
 						      value);
 		}