Add ability to query units from netcdf.

The time units and calendar give you a start time, time step size and
calendar which you can use to interpret what the timestamps mean.
Units on the other variables are likewise a good thing to have access
to.

Change-Id: Iebb151973e53fee120f5d3874aaa3d95401b395b
Add a facility to translate vtkPolyData to GeoJSON format.

GeoJSON is a specialization of JSON tailored to geodata.
This writer can write to a file or string and encodes geometry
topology and a single scalar attribute as a color for web visualization.

Change-Id: I68ff318c7c6a97bbdc8048e3b4068d51ae3d784f
Merge topic 'netcdf_units' into master

d39346dd Add ability to query units from netcdf.
Merge topic 'geojson_writer' into master

b4e358f6 Add a facility to translate vtkPolyData to GeoJSON format.
fix windows compilation

Change-Id: Id83ff9bb06e3120a431e0007001093cf16fa6822
Merge topic 'netcdf_units' into master

7cbcd88c fix windows compilation