VTK commits supporting netCDF CF and NRRD reader enhancements.

These commits satisfy two currently open bugs:

13843 - netCDF CF reader should be more lenient on time units.
13844 - NRRD reader should support ASCII encodings.

Change-Id: I35a92da60a82ead4313400ca495f94ec6e873e09
Merge topic '13843-netCDF-time-13844-nrrd-ascii' into next

e43de0a VTK commits supporting netCDF CF and NRRD reader enhancements.