npmignore entries trump files entries

[zkat]

Previously, files were treated as negated-negated ignores. This made it fairly
tricky to control whether files or .npmignore took priority when deciding whether
a file should be included.

With this change, files are included through a more explicit process, and
any applicable ignores will trump specific files.

[coveralls]

Coverage decreased (-2.4%) to 81.169% when pulling 7e2d046 on zkat/npmignore-trumps-files into d57b6b2 on master.

[sophistifunk]

Has this recently been implemented somewhere? Because this fix has (in the last couple of days) started breaking things where we have dist in our files:[] list but also in .gitignore and running npm publish results in modules without any (code) content. Having to maintain duplicate ignore lists (only one without "dist") is an ugly thing to foist on the users IMO.