[NoVal rework] collection issue
Collection issue for NoVal rework.
1) UI + model change: Add a checkbox to state if the port can be a noVal or not.
2) Update transformation to the model checker
3) Modify code generator accordingly
4) investigate if simulator semantics need to change and change if necessary
Later some static analysis should be incorporated too. Currently I can think of a simple one implemented as a constraint: check if a NoVal port is read in any transition without checking if it is not NoVal