Too much refactoring

Broken it all as I tried to refactor too much at once.
Revert "Too much refactoring"

This reverts commit 57087b81f23fae053ad661b2fc064fe1b631e1fd.
Update library to 2DElements branch of SharpFECore.dll
Formatting of AssembleModelComponent

Mostly white space formatting.
Made set methods of properties protected.  This has required the
constructor signature to be amended to accept lists of elements, loads
and supports.  Tests have been updated in line with this changed
signature.
White space formatting
GH_Model is responsible for creating nodes, not GH_Node
White space formatting

GH_Spring now also delegates to GH_Model for node creation
GH_ConstantStrainTriangle delegates node creation to GH_Model
GH_NodalLoad delegates node creation to GH_Model
GH_NodeSupport delegates node creation to GH_Model

White space formatting of GH_NodeSupport
Removed GH_Node

GH_Node has been removed as nodes are never passed between components.
This has required a significant refactor.  Point3d and
IFiniteElementNode are now used in place of GH_Node.
Further files in addition to 0fd03ea
Calculates and displays Constant Strain Triangular 2D Elements