User_Visible versions of Building Types + HVAC system + Operating System

[eertugrul]

improve Building Types, HVAC Systems and Operating Systems drop down nodes per our discussion on human readable version of the energy setting types, available in Revit API.

@bhowes-tt, this improvement also affect issue #12 Set energy setting node should be revised as well. Please let me know,

[eertugrul]

@mostaphaRoudsari & @bhowes-tt EnergySettings class is now element so the method get_Parameter is only available for Revit 2015
http://thebuildingcoder.typepad.com/blog/2014/04/whats-new-in-the-revit-2015-api.html

[mostaphaRoudsari]

@eertugrul thanks for checking. Good find!

What do you think we should do for this? Make it conditional to version? or just play safe and return the original value?