Version 0.2.0 maintenance/update

[luite]

The package is (mostly) not broken, but there is some maintenance that can be done:

• add functionality introduced by recent macOS (is there anything that should be added?)
• fix deprecation errors, switch to newer API, potentially drop support for very old macOS versions
• remove osVersion, this was originally meant only to query for file level events. they have been supported for a very long time now
• revisit callback model, having a pipe and a pthread for every watch uses more resources than necessary perhaps, maybe we can do without

Any other requests?