Wait until all core extensions are loaded before loading user extensions.
This makes menu ordering more consistent, and fixes bug #5442 where the
order of registration matters.

Also change extension loading to work with arrays most of the time, avoiding
bugs if there are ","s in pathnames.

And fix stale comment in ExtensionManager.
Ensure linting results update when a new linter is registered that might
affect the current file. Linters can register very late due to on-the-fly
Extension Manager installs.
Only show one entry in rule list for rules with multiple matching selectors
Add contentChange event to TextRange. Make it so original change event doesn't fire if boundaries don't actually change.
Update label in rule list when a selector is edited
Merge branch 'css-quick-edit-new-selector' into nj/update-rule-label
Merge branch 'master' into nj/update-rule-label
Rewrite getRangeSelectors() to use extractAllSelectors()
Made unit test for getRangeSelectors() slightly more realistic
Merge pull request #5541 from adobe/nj/update-rule-label

[Initial review] Update rule label when selector is edited
Merge pull request #5493 from adobe/pflynn/load-core-exts-first

Load core extensions before user extensions
Fix JSLint error in CodeInspection.
Merge branch 'brackets' into iwehrman/lo-dash

Conflicts:
	src/editor/MultiRangeInlineEditor.js