Closes #4166

See https://discuss.codemirror.net/t/addoverlay-removeoverlay-and-opaque/835

Closes #4113

Closes #4150

Closes #4152

Issue #3893

Closes #4148

Closes #4140

Fixes issue #4163.

When persistent search dialog is open, looking up commands for findNext/
Prev keys would only search the current keyMap. This commit changes this
to also look up commands in extraKeys

Searching with findPersistentNext or findPersistentPrev will
immediately run a search with the previous query, however it will throw
and error if no previous query exists. This commit fixes by preventing
the immediate execution if no previous query is set

Closes #4149

Closes #4147

Closes #4131

Closes #4130

Closes #4128

Closes #4122

Since the only pre-build version of csslint was changed to some
global-scope-polluting mess that breaks our module loader headers.

Issue #4123

Issue #4112

To match the actual match-highlights in the editor.

Closes #4105

In some cases, on wrapping points, they span the whole line

Issue #4097

Chrome would show the IME widget too high because it noticed the textarea
was cut off by the wrapping DIV.

Issue #4095

In Replace mode (or Overwrite mode) it should still go backwards
without deleting characters.