Refactor roughCount into an atomic QGadget, fix usage of i18np
i18np's first argument should be a valid number. Meanwhile roughCount was a string. Instead we should pass the original number as the plural-deciding argument, while using the formatted string only for the actual substitution.
It is only natural to factor out the counter into a gadget class of its
own, since all of its properties (and their semantics like the
roughCount.length > 0 special case) change atomically and thus do not
require separate connections.
Also, let's store the Timer inline, instead of allocating dynamically.
Replaces !686 (closed)