GH_Beam now creates SharpFE 1DBeam

1DBeam replaces 3DBeam.
Updated SharpFE library dll

SharpFE library is updated.
GH_Node amended to use revised method signature (CreateForTruss is now
CreateFor2DTruss) in updated library.
Formatting whitespace in AssembleModelComponent
GenericCrossSection component added
Test Obj, Bin and Partcover now ignored

Ignoring built libraries within the Test project.
Minor refactoring of GH_Model

Removed redundant namespace path in method signature (the library is
called explicitly, so the namespace of the object can be implied.)