add __enter__ and __exit__ methods to functions with an unload method
tidy some reader syntax
fix container class warnings

UNTESTED!
fix seed numpy type interaction with cython
tidy some reader syntax
fix container class warnings

UNTESTED!
initial mpl plotting changes
use pyplot instead of pylab
add mpl tighten and change colorbar calls to work with that
fix 1d plot labels
add abs_max and abs_min to necalc
mpl plot_opts is working, but I don't like the implementation
fix recursion issue in datasets / grids
add some more simple mayavi wrapping
Merge branch 'feature/p2d' into develop