Which was (possibly accidentally) dropped in the input style overhaul.

Closes #3555

Which wasn't taken into account in this input backend at all,
up to this point.

See http://discuss.codemirror.net/t/read-only-support-in-mobile-safari/470/1

Issue #3257

Issue #2101

Issue #3474

Fixes #3449

* Fix bug where you could paste into a `readOnly` editor
* Show a cursor at the drop location when dragging over the editor
* The [Rust mode](http://codemirror.net/mode/rust/index.html) was
  rewritten to handle modern Rust
* The editor and theme CSS was cleaned up. Some selectors are now
  less specific than before
* New theme: [abcdef](http://codemirror.net/demo/theme.html#abcdef)
* Lines longer than [`maxHighlightLength`](http://codemirror.net/doc/manual.html#option_maxHighlightLength)
  are now less likely to mess up indentation
* New addons: [`autorefresh`](http://codemirror.net/doc/manual.html#addon_autorefresh)
  for refreshing an editor the first time it becomes visible, and `html-lint` for using [HTMLHint](http://htmlhint.com/)
* The [`search`](http://codemirror.net/doc/manual.html#addon_search)
  addon now recognizes `\r` and `\n` in pattern and replacement input

Closes #3457

Should reduce the indentation issues after long lines

Issue #3443

Issue #3434

Also some general improvements to material.css and solarized.css

Closes #2645

Closes #3410

Issue #3401

Issue #3395

Issue #3395

When something is redraw, we definitely need to do the consistency-
ensuring that is done by a display update.

Issue #3387

Issue #3357

Issue #3369

Closes #3361

So that selection inside widgets isn't affected

Issue #3342

So that they don't end up overriding more specific styles.

Issue #3325

Issue #3316

Get rid of webkit paste bug workaround again, since recent
webkits all support the clipboard API.

Issue #3031

It can, if the selection is changed in that narrow window, cause
bogus deletion of the selection.

Issue #3273