[lint addon] Wrap long lint messages

e.g. errors on css `input.someLongClassName {}`
Add handleEx() to Vim mode's API

Provide an alternative (programmatic) way to run Ex commands.
Document a few more addons

Issue #1894
Improve mode writing docs a little, document line- and line-background- tokens
Work around poor italic support for webfont
[continuelist addon] Should continue list even after special chars (space, !, etc)