Name some printer/diploma routines, name wd434, misc. cleanup

[Narishma-gb]

Main changes in this PR are:

• Add a new constant : PIKACHU_SPRITE_INDEX, currently in map_objects_constants.asm
• Name wd434 as wPikachuCollisionCounter : writing a non-zero value makes Pikachu sprite impassable for the player when turning around. There is a countdown of 8 frames until its sprite becomes passable. This allows easy facing/interacting with Pikachu.
• Fix for Are the labels in CheckPikachuFaintedOrStatused wrong? #103 : renamed sublabels and changed name to CheckPikachuStatusCondition
• Simplify IsThisPartymonStarterPikachu_Party/_Box into IsThisPartyMonStarterPikachu / IsThisBoxMonStarterPikachu
• Name some functions in engine/printer/printer.asm
• Remove large tilemaps from asm files, using INCBIN instead
• Diploma graphics and tilemaps are now stored in gfx/diploma, because they are unrelated to surfing minigame
• Change IsStarterPikachuInOurParty into IsStarterPikachuAliveInOurParty, to reflect its behaviour, + comments
• Name remaining symbols in engine/events/diploma2.asm
• Fix a few constants here and there, change a few ldi [hl] > ld [hli]
• Add Yellow-specific Bench guy bug comment

[Rangi42]

Just one more thing; please add NAME_LENGTH_JP to constants/text_constants.asm:

 DEF NAME_LENGTH EQU 11
 DEF ITEM_NAME_LENGTH EQU 13
 DEF NAME_BUFFER_LENGTH EQU 20
+DEF NAME_LENGTH_JP EQU 6

[Rangi42]

Thanks a lot!