Add pprng as dependency, provide large integer seeds
Add transmit to actually infect target S nodes
Add (Pull) specification to traget-ids function
Merge branch 'feature-better-random-numbers' into develop
Create node finders for susceptibles and infectious
Add push alternative functions
Add push versions of target-ids and transmit (passing)
Get require outside ns macro
Delete transmit-push (transmit can take push version)
Switch to the push model completely (passing)
Merge branch 'feature-push-target-ids' into develop

Change to push infection model
Add simulate function skeleton
Add general structure of simulate (untested)
Change comment headers more explicit
Fix unit-time-lapse to return a graph

It previously returned a vector in contrary to
what it claimed to do.
Change transmit to create :E nodes (not :I nodes)
Modify simulate to return a seq of graphs

This is more informative than just returning the state-freq
Add reproducible pseudo-random number to simulate
Change transmit-test to accomodate S->E transition

Before it was expecting S->I transition
Remove probablistic failure from target-ids-test