made the code of rpc_model.py easier to read
tested numpy built-in function polyval3d, and added a few docstrings
minor improvement in common.tmpfile function. Some docstrings added.
corrected the multi-spectral / panchromatic composition of images with a small
(4 pixels) translation in the horizontal direction
updated gitignore
moved the 'run_binary_on_list_of_points' function in common

Minor improvements to this function, and integration into the geographiclib
wrappers.
add docstring
Merge branch 'master' of https://github.com/carlodef/s2p

Conflicts:
	python/block_matching.py
merge