0.13.0

Full Changelog

• Add initial version of code coverage collection
• Improve tests
• Make ureact::transform compatible with invokable that return reference Now
  it works the same way ureact::lift does - invoke result is decayed to deduce
  result ureact::events<E> type
• Add ureact::transform_as to manually select result type instead of relying
  on the deduced type