Allow featureGroup initialization with no overlay corners (publiclab#381

)

* test how readme formatting is rendered

* update formatting

* make documented setters return this

* bump to 0.8.0

* update

* update demo

* fix grammer

* update to use DistortableCollection.Edit

* complete API

* make API make sense

* fix mobile

* update readme

* update cmment

* revert demo change

* revert both demo changes

* refactor

* add new line to end of file

* make final updates

* fix typo

Gruntfile.js

@@ -134,6 +134,7 @@ module.exports = function(grunt) {
             'src/edit/tools/DistortableImage.PopupBar.js',
             'src/edit/tools/DistortableImage.ControlBar.js',
             'src/edit/DistortableImage.Edit.js',
+            'src/edit/DistortableCollection.Edit.js',
             'src/components/DistortableImage.Keymapper.js',
             'src/edit/BoxSelector.js'
           ],