add linear algebra formulations of rates and committors
add rate computation via linear algebra
do some benchmarking for sparse linalg

actualy I've found a problem with it.   Sometimes the returned
times are less than zero.  I think this is because the matrix (after
removing the A nodes) is disconnected.
more work trying and failing to find the bug
found problem with linear algebra calculation

I was loading rates with some rate constants from a minimum to itself.
This was causing errors.
some clean up
more cleaning up
combine linalg tests
add support for multiple A sites
add steady state rate constant calculation

not fully tested yet
committor calculation now uses sparse matrix
add some more tests