MAGN-3394 Structural Framing by curve has too many inputs

http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-3394

This pull request adds three new ways to create structural framing. This addresses the issue in MAGN-3394, of the current structural framing node having too many inputs. There are three new types:

StructuralFraming.BeamByCurve
StructuralFraming.BraceByCurve
StructuralFraming.ColumnByCurve

Requires Merge:
- [ ] Revit2015

PTAL:
- [ ] @Randy-Ma 
If the same family symbol "W12X26" works for both beams and columns, I doubt the usage of the new node StructuralColumnTypes. Could you help double-check that this test case works?