build: use bundle-collapser
view: differentiate sync & paragraphUpdate
test: rich text
richMode/formatInline: remove dead code
richMode: trim trailing <br>s
richMode/view: sync on keypress/composition events

Syncing after keydown meant rich text could not be applied to IME
composition, as the sync would interrupt composition.
test: rich text tests

The browser in which to test is now configurable; to test in Chrome,
for example, one can do:

  BROWSER=chrome npm tst

The browser defaults to Firefox. Because of some kind of webdriver
oddity, the inline rich text tests fail in Chrome; for now, at least,
they are skipped in that browser.