Added DateTime library
added datetime to csproj
added sunsettings nodes
added GetAllElementsFromView node
Add DynamoAnalysis library and make AVF override to use it.
Add Point and Vector Analysis Data types.

Adjust constructors and internal mutators to take those objects.
Add more constructors for analysis types.
Merge remote-tracking branch 'origin/master' into SolarRadiation
Updates to interfaces and analysis data types.
Don't copy DynamoAnalysis local.
Begin constructing IAnalysisModel interface.
Updates to analysis interfaces.
Cull calculation locations not on surfaces.
Add name and description for AVF nodes.
Add Insolation to Units.
Make SolarInsolationAnalysisDisplay

Allows us to send in custom units.
Merge remote-tracking branch 'origin/master' into SolarRadiation
Set the current units.
Update Excel to support iterative writing.

These changes write to already open workbooks or worksheets if they are
found. If they are not found, it falls back to creating them as before.
some cleanup