added A LOT of tests
renamed isMozOrESNext to isAfterESNext;
added isAfterES5;
refactored ESnext/Moz support to raise errors on future features;
fixed several parsing issues

Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net>
updated automatic comma insertion support (cf #950)
added line breaking error on 'return' statement with and without asi option (when it's broken, fix it).