Code simplifications.
Linear insertion balancedness test works.
Linear insertion balancedness test works.
Merge branch 'tree' into re-tree

Conflicts:
	Unittest/RedBlackTreeTest.cs
Started rewrite so that the tree can be a set or map.
All tests pass again.
Added tuple constructor.
Added type restriction to Set.
Added type restriction to Map.
Usings
Empty property for set and test.
Added indexer with test to map.
Clean up.
Renaming of Node.Key property.
Added a Clear() method.
Renaming
Removal seems to work.
Refactored HasRedChildren().
Extracted twice left color method.
Made RedBlackMap implement IDictionary.