Excise the insertion_time_elem_t logic

It's now redundant with the inserted_time field in packed_cell_t

Fixes bug 10870.
Merge remote-tracking branch 'public/no_itime_queue'

The conflicts here were tricky, and required me to eliminate the
command-queue as well.  That wasn't so hard.

Conflicts:
	src/or/or.h
	src/or/relay.c
Merge remote-tracking branch 'public/no_itime_queue_025'