Use TOR_SIMPLEQ for packed_cell_t
Unit tests for cell queues.

This removes some INLINE markers from functions that probably didn't
need them.
Add a test for n_cells_in_circuit_queues
Merge branch 'simpleq_for_cells_3'
Start of a unit test for options_validate.

I added this so I could write a unit test for ServerTransportOptions,
but it incidentally exercises the succeed-on-defaults case of
options_validate too.