Use doublestar for glob matching

[shaxbee]

Enables glob patterns containing ** eg. **/*.go

[shaxbee]

Noticed excludePrefix wasn't working with glob matcher. Added implementation and tests as well.

[shaxbee]

@cespare could you kindly review?

[shaxbee]

@cespare Is there anything preventing this PR from being reviewed?

[carrete]

@shaxbee You may want to check out https://github.com/cortesi/modd

[cespare]

@cespare Is there anything preventing this PR from being reviewed?

Sorry, I find it hard to get excited about this because I've never needed this feature (and because it adds a dependency).

This would also need documentation.

[cespare]

The documentation for the ExcludePrefix method says:

// ExcludePrefix returns whether all paths with this prefix cannot match.
// It is allowed to return false negatives but not false positives.

That is not what this function implements. For example, if the pattern is **/, that matches the prefix a/ but does not match the path a/b.txt. So this would incorrectly exclude a/b.txt from the watch.

It's not immediately obvious to me how to fix this problem. I designed the ExcludePrefix mechanism mostly with regexp matching in mind.