Refactor runEvent for readability
Finish the renaming for challengeblock code
Marty and MJB get custom avatars
Refactor how stats are calculated
They're now read on-the-fly instead of being recalculated and cached
every update.
Fix avatars
We're using the PS rules page again
Fix Relic Song transforming Meloetta twice

- It incorrectly transforms twice in doubles due to being a spread hit
Fix Soul Dew's boosts.
Flare Boost & Toxic Boost are BP modifiers
Fix Swallow healing.
Fix a bunch of bugs in the stats refactor
Consistently call the project 'Pokemon Showdown' in readme
Display helpful message for missing module

This should help users understand that they need to run npm install.