Reduce sizes of THEME_LOC (20->10) and ThemeStruct

Source/gendung.h

@@ -31,11 +31,11 @@ struct ScrollStruct {
 };
 
 struct THEME_LOC {
-	Sint32 x;
-	Sint32 y;
-	Sint32 ttval;
-	Sint32 width;
-	Sint32 height;
+	Sint16 x;
+	Sint16 y;
+	Sint16 ttval;
+	Sint16 width;
+	Sint16 height;
 };
 
 struct MICROS {

Source/themes.h

@@ -13,7 +13,7 @@ extern "C" {
 
 typedef struct ThemeStruct {
 	theme_id ttype;
-	Sint32 ttval;
+	Sint16 ttval;
 } ThemeStruct;
 
 extern int numthemes;

enums.h

@@ -43,7 +43,7 @@ typedef enum dungeon_message {
 	DMSG_DIABLO    = 1 << 4,
 } dungeon_message;
 
-typedef enum theme_id {
+typedef enum theme_id : int8_t {
 	THEME_BARREL            = 0x0,
 	THEME_SHRINE            = 0x1,
 	THEME_MONSTPIT          = 0x2,