Code cleanup

These are all general issues with the pokecrystal code. Keep an eye out for opportunities to refactor them.

Reformat code to adhere to STYLE.md. (Converting labels to .snake_case is one that stands out.)

As of 0.3.7, we have these features that are little-used:

~ works for bytes, so we can do ~X instead of $ff ^ X
HIGH() and LOW() work for constants
BANK(@) gets the current bank; BANK("Section Name") is also valid (some labels can thus be removed)
\ continues lines, like in C or Python, which could help clean up long macros (trainer, npctrade) and implement new ones (like for data/trainers/attributes.asm or data/pokemon/base_stats/*.asm)

Look for UnknownText_*, UnknownScript_*, Unknown_*, and Function_*.

Most of the time, raw numbers should not exist because there are more meaningful replacements. Examples:

BANK(Label): Mostly finished for WRAM labels, but still a problem with mobile code.
SomeLabelEnd - SomeLabel: Some structs and sub-structs still have hard-coded sizes like this.
(SomeGFXLabel.End - SomeGFXLabel) / LEN_2BPP_TILE: pokered and pokegold-spaceworld already do this.
Bit flags: Use SOME_BIT_F constants instead of hard-coding bits 0-7 for the bit/res/set instructions. Find opportunities with:
```
  grep -rE --include='*.asm' --exclude-dir=mobile '^\s(bit|res|set) [0-7],'
```
Bit masks: Use 1 << SOME_BIT_F masks and the maskbits macro.
Jumptable indexes: Look for raw values being loaded into [wJumptableIndex].

Currently a mixture of Text_*, *Text, and BattleText_*. Likewise for the engine/ labels that just text_jump to one of them.

Curr -> Cur
wMapObjects and friends to be re-formatted to wObjectEvents
wObjectStructs and friends to be re-formatted to wMapObjects
Removal of struct macros which include only a partial label definition (e.g. wNorthMapConnection:: map_connection_struct wNorth)

Namely determining the purpose of them and when they should be defined.

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