Testing closing of several dialogs

Testing opening and closing of:
- git-clone action
- help-about action
- new-project action

Also:
- setup transition-complete event on spark-overlay and listen for it in tests
- refactor access classes into separate file.
- fix several nit issues (copyright and library names)
- checking visibility with `elementFromPoint` instead of `display` / `visiblility`

@devoncarew @ussuri 
Unfortunately, no.  There are several transition-complete events and I just want the first.  I could move the tick-cycle (Duration.ZERO) to the top of the codeblock, though.  That would probably be less confusing.

Unless you're referring to the placement of the .then.  I just like to consistently keep them at the beginning of the line to clearly show where async-breaks are.  I am happy to use another convention as long as it's consistent.