2014-08-20  Gerrit Holl  <gerrit.holl@utoronto.ca>:

	* pyatmlab-0-0-42

	* pyatmlab/collocations.py(CollocationsDescriber):

	- In smoothing, take care of the situation when xa and A come from
	another source and are not on the same vertical grid, so that
	interpolation is needed.  Only partially tested, likely still buggy.

	* pyatmlab/constants.py: +hecto

	* pyatmlab/dataset.py(Dataset):

	- Add method get_additional_field, not implemented here

	* pyatmlab/datasets.py: get hecto from constants

	* pyatmlab/math.py:

	(regrid_ak): Move W*A*W' to separate function

	(apply_W_A): Actual W*A*W'

	* pyatmlab/physics.py:

	(p2z_hydrostatic): Optionally extend p/t/q, USE AT OWN RISK,
	assumptions wholly inappropriate if extending is far!