Support for negated Ignores Globs

[arciisine]

Looking back at the PR (#106), support for ignore globs was added about a year ago. The glob implementation supports negation on a per rule basis, but it appears when checking if something is ignored or not, a negated glob is not treated as an escape hatch.

As far as I can tell, given the current pattern, negated globs have no impact as the logic for ignore resolution only cares if the match is positive.

https://github.com/parcel-bundler/watcher/blob/master/src/Watcher.cc#L224-L230

Ideally this would behave similar to .gitignore, so I could ignore node_modules/**, and then allow a specific folder underneath that with an exclusion.