added exception reporting for tasks in IDESolver
bugfix: when propagating inside out into a caller that was not yet processed we need to create a summary edge starting at ZERO, not at the callee's flow fact!
shutdown now
Merge branch 'develop' into feature/exception-handling

Conflicts:
	src/heros/solver/IDESolver.java
improved handling of number of threads (thanks Johannes!)
Merge branch 'feature/exception-handling' into develop