add example solutions to (default) instances for Reach.Reach and Reach.Deadlock

[jvoigtlaender]

In all these places:

modelling-tasks/example/src/Modelling/PetriNet/PetriReach/Instance.hs

Lines 49 to 50 in ae29a30

	maxDisplayedSolutions = 1,
	shortestSolutions = Left ([] :| []), -- TO DO: add a solution here

modelling-tasks/src/Modelling/PetriNet/Reach/Deadlock.hs

Lines 327 to 328 in ae29a30

	maxDisplayedSolutions = 0,
	shortestSolutions = Left ([] :| []), -- TO DO: add a solution

modelling-tasks/src/Modelling/PetriNet/Reach/Reach.hs

Lines 624 to 625 in ae29a30

	maxDisplayedSolutions = 0,
	shortestSolutions = Left ([] :| []), -- TO DO: add a solution

modelling-tasks/example/src/Modelling/PetriNet/PetriDeadlock/Instance.hs

Lines 42 to 43 in ae29a30

	maxDisplayedSolutions = 1,
	shortestSolutions = Left ([] :| []), -- TO DO: add a solution here

the first occurrence of [] should be replaced by a correct solution (and maxDisplayedSolutions be set to 1 where it isn't already).