Add param documentation for VPrintable.
Add 429 status code to VRatelimit.
Generalize strict validation error abort method.
Web frontend logging.
Catch and log errors setting local storage values.
Add missing error status code to VPrintable.
safeGet/safeSet: Don't bother if store.js is disabled.

For IE with localStorage disabled, store.js can raise exceptions if you
attempt to use it when it is "disabled" (cannot select a backend).
Report JS errors during base initialization.