Bump sbt version number
Moved the representations to models.domain.scala
remove unused val
Rename files to match classes, clean up imports
remove todo
legalNeighbours does an intersect with the neighbours for the node, canTerminate no longer needs to be memoizing
removed nulls from spec
call by name the possible children to save doing work when not required
added override to neighbours and removed type annotation
Jacoco for code coverage