closes#2957
- add FastClick library to Gruntfile.js
- add touch-editor to client/assets/lib/
- add mobile-specific utils to util/mobile-utils.js
- add codemirror util to set up TouchEditor only if we're really on mobile
- change gh-codemirror from having a default action to a named action. prevents Ember.TextArea firing action on change
- change gh-codemirror `cm.getDoc().getValue()` to `cm.getValue()` for portability
- change codemirror-shortcuts ES6 export/import style
- changed ghostimagepreview.js to check for Ember.touchEditor in addition to Ghost.touchEditor
Closes#2984, #3020
Ref #1463, #3019
#### Shortcut Values
Shortcut values can now be either strings (as before) or objects like
{action:string, options:hash}.
#### Markdown shortcuts added
- 'ctrl+alt+u' strkethrough
- 'ctrl+alt+1' h1
- 'ctrl+alt+2' h2
- 'ctrl+alt+3' h3
- 'ctrl+alt+4' h4
- 'ctrl+alt+5' h5
- 'ctrl+alt+6' h6
- 'ctrl+shift+i' image
- 'ctrl/command+k' link
- 'ctrl+l' list
Left behind commented out stubs for additional markdown shortcuts.
#### Editor Controllers (New and Edit)
- Moved shared init function into editor-base-controller.
- Removed MarkerManager mixin from editor controllers as it's included in
the base.
