endTiming now returns timing measured

disclaimer: this change makes it easy for me to scratch a personal itch

The method Client->endTiming() now returns the time that is being measured.  This then allows that value to be used without recalculating it (my example is I want to log slow sections that I am recording via start/endTiming)

A negative to accepting this is that Client->time returns the result of the Closure and not the time taken - which means this change could be seen as inconsistent.