Use CreateInsertModeChanges to make a copy of the latest
insert mode changes in pushInsertModeChanges so that the
latest insert mode changes can safely be modified without
bashing previously recorded macros.

Fix the :register command and add unit tests. Add a fakeOpenNotification for matching the notification text.

Issue #2326

Issue #2326

It causes noticeable missinge scrollbar in some cases.

Closes #2317

pressing Ctrl-Space once starts the selection extension mode,
pressing it again cancels that

It was broken and confused.

Make the mode register a list of completable words instead.

Issue #2324

In Vim, defaults keymap cannot be unmapped. They must be explicityly
set to <NOP>. In this case we allow that because
user defined maps are stored in the same map as the defaults.

Closes #2331

If a line has widgets with heights, use them when estimating line height.

This prevents a .refresh() call from reverting to less accurate line
heights.

Issue #2323

And listen for them in the merge addon.

Per change authored in https://github.com/marijnh/CodeMirror/pull/1979.

Closes #2309

Issue #2304

Closes #2200

Issue #2283

Issue #2282

Closes #2275

Closes #2274