Reinvestigate frozenset suitability for sequence independent membership checks

[ktnr]

Frozen sets are sequence dependent when instantiated from lists but not when instantiated from tuples or sets?

For example, in

BinPacking2D/BinPacking.py

Line 589 in 3d2852a

if frozenset(itemIndices) in model._InfeasibleSets or frozenset(itemIndices) in model._IncompatibleItems:

membership is compared after adding items to the collection of frozensets from lists

BinPacking2D/BinPacking.py

Lines 673 to 676 in 3d2852a

	if frozenset(itemIndices) in model._FeasibleSets:
	continue
	if frozenset(itemIndices) in model._InfeasibleSets:# or frozenset(itemIndices) in model._IncompatibleItems:

So there might be many entries with the same items but in different sequence. As a result, subproblems will have to be solved multiple times even though they have already been proven feasible or infeasible before.