Check for valid codeSnippet.
change delete and create node methods to be synchronous
Merge pull request #6421 from adobe/nj/cm-sprint36-monkeypatch

Monkeypatch CodeMirror for sprint 36 to include latest xml mode
fix special case for project root
remove _fileTreeChangeQueue
remove shallow search option. optimize findTreeNode.
Fixed line number color bug.
cleanup added file filtering
Use a memoized comparator for jsTree sorting
Comment typo
Update screenshots for all languages. Move -webkit-font-smoothing to html so it doesn't show as invalid in the body rule in screenshots.
Respond to review comments.
Fix references to PreferencesSystem in PreferencesManager
Updated by ALF automation.
fix 6450
add help menu item to open prefs file
Merge branch 'master' into PreferencesModel

Conflicts:
	src/language/CodeInspection.js
Fix CodeMirror submodule
Fix handling of pref changed event for collapsed in CodeInspection
Fix menu enabled state for editor options, save CodeInspection changes