RGBDS syntax updates (#905)

New MACRO and DEF syntax

engine/movie/intro.asm

@@ -1438,19 +1438,19 @@ endr
 	ret
 
 .FastFadePalettes:
-hue = 31
+DEF hue = 31
 rept 8
 	RGB hue, hue, hue
-hue -= 1
+	DEF hue -= 1
 	RGB hue, hue, hue
-hue -= 2
+	DEF hue -= 2
 endr
 
 .SlowFadePalettes:
-hue = 31
+DEF hue = 31
 rept 16
 	RGB hue, hue, hue
-hue -= 1
+	DEF hue -= 1
 endr
 
 Intro_LoadTilemap:

engine/movie/trade_animation.asm

@@ -1,5 +1,5 @@
-TRADEANIM_RIGHT_ARROW EQU "▶" ; $ed
-TRADEANIM_LEFT_ARROW  EQU "▼" ; $ee
+DEF TRADEANIM_RIGHT_ARROW EQU "▶" ; $ed
+DEF TRADEANIM_LEFT_ARROW  EQU "▼" ; $ee
 
 ; TradeAnim_TubeAnimJumptable.Jumptable indexes
 	const_def
@@ -7,14 +7,14 @@ TRADEANIM_LEFT_ARROW  EQU "▼" ; $ee
 	const TRADEANIMSTATE_1 ; 1
 	const TRADEANIMSTATE_2 ; 2
 	const TRADEANIMSTATE_3 ; 3
-TRADEANIMJUMPTABLE_LENGTH EQU const_value
+DEF TRADEANIMJUMPTABLE_LENGTH EQU const_value
 
-add_tradeanim: MACRO
+MACRO add_tradeanim
 \1_TradeCmd:
 	dw \1
 ENDM
 
-tradeanim: MACRO
+MACRO tradeanim
 	db (\1_TradeCmd - DoTradeAnimation.Jumptable) / 2
 ENDM
 
@@ -1428,7 +1428,7 @@ DebugTrade: ; unreferenced
 	jr nz, .loop2
 	ret
 
-debugtrade: MACRO
+MACRO debugtrade
 ; species, ot name, ot id
 	db \1, \2
 	dw \3