Use labels for all break and continue statements. Related to #1271, because I want
to be able to transform a switch to a Java switch, but I need to ensure the
break transformation doesn't get broken.
Bulk update tests now that for/while/break/continue are always generated with labels. (Related to #1271)
Fix #1271: Optimize the switch statement:

* If we have to transform a switch to an if/else chain, avoid boxing when performing the equality tests
* Use a Java switch rather than if/else chain when switching over String or Character literals (not Integer literals, because Java doesn't support switching on long).
Issue #1271: Improve tests for value switches.