Fix #5275: $1 and so on now work with replacing with RegEx

Fixes #5275
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Add Menu.removeMenuDivider()
Add Menu.removeMenuDivider unit tests
Remove all menu items before removing menu
Fix problem with removing dividers.  Add remove menu (native) unit tests.
Merge remote-tracking branch 'upstream/master' into patch-6
My try to improve the replace() function
Fix URL hints not showing
Fix for adobe/brackets#5426
Make the project-dropdown-toggle toggle the dropdown menu
Allow event propogation even when there is no dropdown item.
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.
Update 'de' locale for sprint 33
add placeholder button to css inline editor
Fix wrong path of Getting Started directory in Polish version
Add addNewRuleToDocument() function
Add addAndSelectRange() function to MultiRangeInlineEditor
Add _addRule() to CSSInlineEditor
changing not.toBeNull to toBeTruthy
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