Initial commit of adapthist modifications.
Tests pass and example works on build.
Added Notes to the docstring.
Pep8 fixes.
Replaced generic ACM license with the Graphics Gems IV license.
Improved support for color images using lab transform.
Passed all tests with full coverage, PEP8 and Pylint performed.
ENH: Allow imread to read URLs
Fix handling of temporary file.

Opening an already-opened file was unsafe. Close the file, then manually delete it.
ENH: Add test and support for reading file URLs
STY: Fix confusing use of context-manager.
Translated clahe C code to python, added to list of contributors.
Removed sys.path hack in test, fixed spelling of import in __init__.py
Add gabor filter function
Fix meshgrid bug in gabor kernel and argument passing
Add test cases for gabor filter
Add example script for gabor filter
Remove unnecessary kernel description for filtering
ENH: Add canvastools subpckages with base class and line tools
BUG: Move callback connection to parent class