Default this to true when the fat-cursor style is active.

Issue #4803

Closes #4128

Add a dummy ContentEditableInput

Bumping them for every release just adds too much git
noise and history blowup.

Issue #2442

Issue #778

Use it to make xml-fold more robust, and matchbrackets much faster.

Without a bunch of more involved code, it has quadratic complexity, which
gets slow rather fast.

Closes #1408

Issue #1408

Issue #1242

This helps performance on v8 (in microbenchmarks) and is less noisy.

Regular literals are still accepted, the constructor is only used to create
objects, doesn't attach any methods.

Where it mysteriously makes the editor stop working (typed input no longer goes to
textarea) whenever highlighting fires.

Issue #1193

Closes #1133

className is misleading -- these are not the actual CSS classes.

As spotted by the extended linter.

The class is now specified as an option, rather than a separate argument
(and is thus optional).

Incompatible API change.

The off pun is rather awful, but it does have precedent, and is
more succinct.

It was passing undefined to setTimeout.

Add CodeMirror.defineOption function for defining new options.

Add findMatchingBracket to the methods exported by this extension.

Closes #746