Move hinting functions into it.

Issue #1084
Issue #1630

+ a few other fixes

Issue #1625

Issue #1616

Which had been accidentally removed.

Issue #1567

(Old newFoldFunction interface preserved for backwards-compatibility.)

When implicitly activating completion, it is undesirable.

Using some of the ideas from the html5 hinter. Can now
use a much richer source of hinting information, and also
completes properties and property values.

Example usage: applying different color schemes to submodes.

A dash is only handled specially when preceded by a word character.

Issue #1531

Too specialized. Out of scope.

It's flaky, and I don't want to support it.

Everybody: feel free to take the code, put it in some other repo
and maintain it.