2014-10-03  Gerrit Holl  <gerrit.holl@utoronto.ca>:

	* pyatmlab/collocations.py(CollocationDescriber):

	- Add method to plot aks
	- Add no. of profiles to comparison plots

	* pyatmlab/dataset.py(Dataset):

	- use mutable cache for combine

	* pytmlab/datasets.py:

	- Add ak alias