Added a hook on SLTest for getting notified when an exception happens in a test run.
Added a SLTestCaseExceptionInfo object which encapsulates the relevant exception data.
Added documentation for `SLTestCaseExceptionInfo` and the corresponding hook on `SLTest`.
Merge remote-tracking branch 'public/master' into add-exception-info

* public/master:
  Support for using a prebuilt app instead of building one (fixes #207)
  Incorporate PR feedback
  Allow SLAssert methods to be called from non SLTest subclass methods
  `-[UIView slAccessibilityIsVisible]` now reports an element's visibility on-screen, regardless of window. (fixes #212)
  Make `SLPickerViewTest` 64-bit compatible.

Conflicts:
	Sources/Classes/SLTest.m
Get our Subliminal back on public master
Merge in latest gazelle/add-exception-info branch
Fix the UIA path generated for Alert items by not removing its content view from the trimmed path
Make dismissByUser accessible always if desired
Better fix to the alert path without requiring private symbols
Fix out-of-bounds index exception for JS exception failures in subliminal-instrument
Give textFields some time to appear before checking that they have keyboard focus
Enhance the full hiearachy swizzle helper and rename it something more appropriate
Catch the alert handler exception
Fix Documentation for debug helpers
Add the fix to SLTextView and SLWebTextField/View as well
Use SLAssertTrueWithTimeout instead of a custom wait method
Don't rethrow the exception, just splice out the alert handler
Try and hack fix the stupid alert
Add the fix to SLTextView and SLWebTextField/View as well
Use SLAssertTrueWithTimeout instead of a custom wait method
Only parse a string as UTF8 once we have a full line to parse