Add some more ba graph hard-coded examples for regression testing
Add ba-graph for testing
Add I->X transition mock up (passing)
Merge branch 'feature-IX-transition' into develop
Add set-field-node function that works on node object
Add related set-*-node functions
Merge branch 'feature-node-obj-update-funs' into develop
Change probability map name
Add title
Add transition rate template
Add preliminary implementation of I->R transition
Change function name to unit-time-lapse for clarity
Overload arity of states function

states function now can take a graph and id-seq to return states of these
Add preliminary functions for stochastic transmission
Add mock up function for stochastic transmission
Add explanation and test for transmission function
Add partially functional version of transmission checker
Define transmission probabilities for all states (0 for none)

Non-infectious states need  probabilities 0.
Each susceptible person will meet up to 10 connected people.
Each encounter must be assessed for transmission, thus,
even the susceptible person (non-infectious) must have
transmission probability defined as zero.
Merge branch 'feature-IX-transition-full' into develop

Add unit-time-lapse simulator
Add stochastic infection target chooser
Merge branch 'develop' (Add time lapse and transmission target chooser)