[gas mode] Fix undefined var error
Prevent bogus error messages when a mode throws an error
Add maxHighlightLength option
Reset hidden textarea when swapping an editor's document
Add moveInputWithCursor option
Use empty changes array when calling updateDisplayInner() subsequent times
Make scrollIntoView work properly when called inside an operation

Closes #1398
Don't blink the cursor when the editor is not focused.

Saves on layout computations.

Closes #1044
Don't run the cursor-blinking timeout at all when not focused
Add XQuery tester to real-world uses
Don't treat whitespace as an error, instead just eat the whitespace (fixes #1331)