add current and previous documents to currentDocumentChange event

[zaggino]

Useful nit to avoid calling DocumentManager.getCurrentDocument() everytime when hooked on the event and also the only way to know what was the previous document I think.

[marcelgerber]

Why don't you use an associative array?
I'd take {current: _currentDocument, previous: previousDocument}

[zaggino]

triggerHandler gets arguments in an array and then spreads them to the callback like this:
https://github.com/zaggino/brackets-git/blob/43d62647ca8d8747f1cc649019f08bc451440fcf/src/BracketsEvents.js#L51-L56

[lkcampbell]

+1 for this. I actually wish every Change event we have provided a newState and an oldState. Would save on maintaining cached states.

[peterflynn]

@zaggino This looks good -- but please just update the docs at the top of the module to indicate the new 2nd & 3rd args.

[zaggino]

@peterflynn done

[TomMalbran]

Should be the second and third arguments, since the first is always the event itself.

[zaggino]

Yes, sry. Early morning here :) Fixed

[peterflynn]

Looks good now -- thanks!