RGBDS syntax updates (#905)

New MACRO and DEF syntax

constants/npc_trade_constants.asm

@@ -1,16 +1,16 @@
 ; npctrade struct members (see data/events/npc_trades.asm)
 rsreset
-NPCTRADE_DIALOG   rb
-NPCTRADE_GIVEMON  rb
-NPCTRADE_GETMON   rb
-NPCTRADE_NICKNAME rb MON_NAME_LENGTH
-NPCTRADE_DVS      rw
-NPCTRADE_ITEM     rb
-NPCTRADE_OT_ID    rw
-NPCTRADE_OT_NAME  rb NAME_LENGTH
-NPCTRADE_GENDER   rb
-                  rb_skip
-NPCTRADE_STRUCT_LENGTH EQU _RS
+DEF NPCTRADE_DIALOG   rb
+DEF NPCTRADE_GIVEMON  rb
+DEF NPCTRADE_GETMON   rb
+DEF NPCTRADE_NICKNAME rb MON_NAME_LENGTH
+DEF NPCTRADE_DVS      rw
+DEF NPCTRADE_ITEM     rb
+DEF NPCTRADE_OT_ID    rw
+DEF NPCTRADE_OT_NAME  rb NAME_LENGTH
+DEF NPCTRADE_GENDER   rb
+                      rb_skip
+DEF NPCTRADE_STRUCT_LENGTH EQU _RS
 
 ; NPCTrades indexes (see data/events/npc_trades.asm)
 	const_def
@@ -21,7 +21,7 @@ NPCTRADE_STRUCT_LENGTH EQU _RS
 	const NPC_TRADE_CHRIS  ; 4
 	const NPC_TRADE_KIM    ; 5
 	const NPC_TRADE_FOREST ; 6
-NUM_NPC_TRADES EQU const_value
+DEF NUM_NPC_TRADES EQU const_value
 
 ; trade gender limits
 	const_def