Previously moves like Leech Seed incremented residualdmg when used by 1,
but this doesn't actually happen in the game. Instead, an actual game
uses a flag to store toxic poisoning flag, and when it's not specified,
these statuses always dealt 1/16 of full HP.
This fixes the issue where the sequence of moves (Toxic followed by Leech
Seed) was dealing 1/16, 3/16, and 4/16 of full HP in residual damage,
instead of 1/16, 2/16, and 3/16.
Steel-types are immune to the poison status in Gen 3+, so wrap it into the
"fail when the opposing Pokemon is immune to the status it sets" and set
up the poison-inflicting status test to check Generation 2.
Spin off Thunder Wave to its own test, and also create a test for Glare to
check its Generation 3 behavior as well.
- Streams are merged to make sure that all errors and warnings are reported.
- Adds dev dependencies: `merge-stream` and `lazypipe`.
- Tracks a fork of `gulp-jshint` to fix https://github.com/spalger/gulp-jshint/issues/88
