Output detailed time information in Solution View for testing.
Prototype of running position solutions from a timer ISR.

Uses the position solution time feedback to align the next timer ISR with the GPS second.

Works with accuracy of a few 100ns. Next should try filtering dt as its a little noisy.
Solution timer now works with arbitrary frequency.

Also cleaned up in solution_view.py
Merge pull request #8 from fnoble/solution_timer

Solution timer