N1QL grammar online editor/tester

I've just added `N1QL` grammar to https://mingodad.github.io/parsertl-playground/playground/ an `Yacc/Lex` compatible online editor/tester (select `N1QL parser` from `Examples` then click `Parse` to see a parser tree for the content in `Input source`).

I hope it can help develop/debug/test/document `N1QL` !

Any feedback is welcome !