for an action to be a candidate, it must be meet precondition in the current cycle AND should not conflict with the already-selected actions and their postconditions
execution implemented ( adds to/removes from database)
node removed when it was on EXIT node
zoom action happens about the mouse position (zoom to mouse position)
translate also changed into Translate (Transform) object
corrected the translation limit for scrolling
zoom action added to domainTheory view
comments added
database view zooming discarded, style refined
goal definition style added (using Stackpane)