Merge branch 'pull-request/1284'

* pull-request/1284:
  Rename interface macros
  Fix typo in UPGRADING
  Move definition of Throwable to zend_exceptions.h/c
  Check for zend_ce_throwable instead
  Fix some missed tests
  Add Throwable tests
  Fix previous exception type check
  Updated UPGRADING with RFC link
  Changed AssertionException to AssertionError
  Update exception error messages
  Throwable method signatures.
  Update exception names in tests after formatting changes.
  Merge exception formatting changes.
  Make zend_get_exception_base static.
  Fix a few missed tests.
  Fix handler double copy.
  Updated tests to reflect exception class changes.
  Remodel exceptions based on Throwable interface