To preserve existing change/cursorActivity handler ordering

Issue #2467

Issue #2464

I.e. don't fire for a handler that wasn't registered when the change happened.

Issue #2463

This change is for enabling the display update while inputting text via the input method.

Issue #2457

This reverts commit 475b2be0.

Issue #2452
Issue #2384

When the call didn't result in an actual change (for example
line already had the given class), changeLine would return null.

This doesn't seem useful, and caused issue #2438. It now always
returns the line handle (as documented).

Also fix Erlang mode to not return a non-standard token type.

Issue #2435

Issue #2427

Closes #2431

(It'll leave space for a scrollbar to the right of the sizer, though the
scroller does not actually have a scrollbar.)

Issue #2420

Issue #2412

To prevent gaps when browsers interpret fractional numbers oddly.

(Experimental for now. Prompted by indentation guide discussion.)

When line numbers are off, and the editor was initialized in
a hidden position, the gutters would sit on top of the text.

Issue #2365

Wrap FileReader.onload in operation.

Issue #988

Issue #2382

Issue #2360

Issue #2355

(It wasn't working in the first place.)

Issue #2390

Issue #2390