Some updates here and there in contact implementation.
Refactoring alot of the code for the contact implementation. + Added a test case for node 2 edge contact using the penalty method.
More refactoring of the contact implementation.
Added StructuralContactElementLagrange for general support of enforcing contact with Lag. multpliers.
Convergence is however bad for node2Edge.
Fixed bug in implementation using Lagrange multipliers in contact and other cleanup.
Updated test case for node2edge contact so it tests Lagrange Multiplier method as well.
Bug fixes in StructuralContactElement and ContactPair.