Saves 16-bit images

Reconstructions done in chunks produce 16-bit .tif files. Reads the
range of values from a middle slice of the sample and scales all slices
according to these min and max values.
Reconstruction Function

reconstruct.py defines a reconstruction function for 180Data.
run_reconstruct.py has a script to run in terminal to call this
function. Hopefully, this will make running reconstructions user
friendly.
Scripts used at Argonne July 2014
Routine Save 08/12/14

Ignore .tif files. Reconstruct does not save 16 bit images.