Issue #1617

Closes #1533

... that caused certain jade files to cause brackets to hang

+ a few other fixes

Issue #1625

(f674dd14)

Closes #1612

Issue #1627

Issue #1625

Work around percentage width rounding problems.

Also makes sure that no two hinting dialogs can be active at the
same time.

Issue #1619

* simpler concat
* less escaping
* shave a line
* throw early
* throw new error
* single quotes
* format returns
* rm unneeded parens
* add whitespace
* re-add braces

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

As a micro-optimization, and to prepare for the next patch.

Issue #1616

cm. -> builder.cm