Single file build guide
Merge pull request #278 from bjornharrtell/buildguide

Single file build guide
Warn when map has fallThrough != true
Explain why `fallThrough:true` is recommended.
Merge pull request #279 from marcjansen/warn-fall-through

Warn when map has fallThrough != true
More details when warning (fallThrough != true).
Merge pull request #280 from marcjansen/better-warning

More details when warning (fallThrough != true).