Add grammar scope to EditorView

Only works when the `grammar-changed` event has been triggered,
and only implemented for Space Pen views.
Use data attribute instead of CSS classes
Make sure the scope data attribute is always set
Implement support for React Editor
Change attribute name to `data-grammar`
:white_check_mark: Add test to verify implementation
Dont handle ctrl+click mouse events on OSX

Ctrl+click on OSX brings up the context menu. In that case, handling the click
event deselects any selection, and that shouldn't happen. See
https://github.com/atom/atom/issues/3308.
:bug: Fix incorrect assertions
Upgrade to language-mustache@0.10
Merge pull request #2996 from thomasjo/editorview-grammarscopes

Add grammar scope to EditorView
Add react editor view spec for data grammar attrs
Merge pull request #3371 from atom/iz-fix-context-menu-again

Dont handle ctrl+click mouse events on OSX
Only emit the marker-created event when the marker exists

This caused problems in the case of find-and-replace:select-all with 
multiple editors into the same file. 

* a marker is created on the TextBuffer capturing the selection
* DisplayBuffer:create-marker is fired from the first DisplayBuffer. 
The marker is turned into a selection which is merged into the current 
selection, deleting the marker that was created.
* DisplayBuffer::handleBufferMarkerCreated is called on the second
DisplayBuffer. The marker has been destroyed at this point, so it emits 
DisplayBuffer:create-marker with undefined. 
* ERROR>

Closes #3364
Merge pull request #3376 from atom/bo-marker-in-splits

Only emit the marker-created event when the marker exists
Require the react-editor-view where we require the editor-view
Fix the mini-editor test
Remove the editor-view
Merge the react and non-react editor styles
:memo: fix return doc
Rename ReactEditorView -> EditorView