Update npmignore

I've added a number of entries to the `.npmignore` that shouldn't be needed in the npm package (and sorted them alphabetically, folders first, for clarity).

**But I'm wondering if tests and test resources are needed in the npm package?** IMO those are things interested people will take from Github if they want, it's just wasting bandwidth (with tests the package gzipped is ~440 kB, without them < 20 kB). What do you think guys?

PS> you can test what will be included in the npm package with `npm pack`