ENH: defined image subtraction function and docstring
ENH: defined image subtraction function
ENH: Defined initial master list of dictionary keys for core library
ENH: added file placeholder for conversion from spec files to nsls2 data format
ENH: Improved dictionary key descriptions
Merge pull request #5 from ericdill/playground

Playground
DEV: Added fileops module to new io folder in nsls2

This module contains basic fuctions for loading common image file types
including netCDF, tiff, raw, some HDF5 functions, and the original
extension-based parent loader load_reconData
DOC: Fixed file tree
Merge pull request #6 from ericdill/spec_input

DOC: Fixed file tree
REF : proposed modifications to img_subtraction_pre
Merge pull request #9 from tacaswell/dc_fixup

REF : proposed modifications to img_subtraction_pre
STY: Fixed all but 1 PEP8 violations
          Merge branch 'master' of https://github.com/NSLS-II/NSLS2

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