Full tests for SeqEns.strict_can_*
Full tests for SeqEns.strict_can_*

Still need similar tests for some of the other test classes that build
atop SeqEns.

choderalab/openpathsampling,openpathsampling/openpathsampling,dwhswenson/openpathsampling,jhprinz/openpathsampling,openpathsampling/openpathsampling,jhprinz/openpathsampling,openpathsampling/openpathsampling,choderalab/openpathsampling,openpathsampling/openpathsampling,dwhswenson/openpathsampling,dwhswenson/openpathsampling,jhprinz/openpathsampling,choderalab/openpathsampling,dwhswenson/openpathsampling