big cutouts

"pure" python implementation of a subroutine that downloads TDB cutouts.
Most importantly, the "get_big_cutout" function from cutout.py can
generate large cutouts (including full frames) locally, while
downloading reasonably sized files from the server.
big cutout works for pressure

and the hdf5 data structure has the proper shape.
existing chunks are not overwritten

even if the file contains junk, it is not overwritten. just delete the
files that are junk.
Merge branch 'develop'
adds (soap) turblib wrapper
adds test
Merge branch 'develop'
bugfix: import numpy
bugfix: import ctypes
bugfix: import sys as well
add dbinfo dictionaries
add channel info
bugfix
misc
add channel grid
use actual channel grid
add generic splines

well, these should be in their own repository, but pyTDB should be as
self-contained as possible.
add function to generate interpolator
Merge branch 'dev' into develop
Merge branch 'develop'