Pkmn -> Mon

Since we're aiming for consistency across the codebase, I believe it
includes a uniform way to refer to the creatures this game consists of
in the labels of the code.
The only exceptions to this rule are labels referring to things named
through the use of the <PK><MN> or <PKMN> characters, in which case PKMN
is used.

Most of this was already consistent enough™, I just picked the
convention with the most occurences and fixed the outliers.

engine/save.asm

@@ -74,7 +74,7 @@ Link_SaveGame: ; 14ab2
 	ret
 ; 14ac2
 
-MovePkmnWOMail_SaveGame: ; 14ac2
+MoveMonWOMail_SaveGame: ; 14ac2
 	call PauseGameLogic
 	push de
 	call SaveBox
@@ -86,7 +86,7 @@ MovePkmnWOMail_SaveGame: ; 14ac2
 	ret
 ; 14ad5
 
-MovePkmnWOMail_InsertMon_SaveGame: ; 14ad5
+MoveMonWOMail_InsertMon_SaveGame: ; 14ad5
 	call PauseGameLogic
 	push de
 	call SaveBox
@@ -119,8 +119,8 @@ MovePkmnWOMail_InsertMon_SaveGame: ; 14ad5
 	ret
 ; 14b34
 
-StartMovePkmnWOMail_SaveGame: ; 14b34
-	ld hl, Text_SaveOnMovePkmnWOMail
+StartMoveMonWOMail_SaveGame: ; 14b34
+	ld hl, Text_SaveOnMoveMonWOMail
 	call MenuTextBox
 	call YesNoBox
 	call ExitMenu
@@ -1203,7 +1203,7 @@ Text_SaveOnBoxSwitch: ; 0x152a1
 	db "@"
 ; 0x152a6
 
-Text_SaveOnMovePkmnWOMail: ; 0x152a6
+Text_SaveOnMoveMonWOMail: ; 0x152a6
 	; Each time you move a #MON, data will be saved. OK?
 	text_jump UnknownText_0x1c465f
 	db "@"