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
STY: Reuse ThickLineTool in LineProfile
BUG: Fix blitting behavior in canvastools
STY: Refactor parts of LineTool to CanvasToolBase
BUG: Clean up imports
Fix figure canvas creation.

Avoid use of matplotlib's pyplot functions for creating figure canvases. In particular, key press events were ignored by the canvas.
BUG: Allow slider to accept key press events
ENH: Default to blitting

Since the Qt4 Agg backend is always used, it's always safe to use blitting.
BUG: Fix background update when canvas resized
STY: Remove commented out code
BUG: Fix blitting behavior
STY: Clean up unused blitting-related code
STY: Minor code clean up
ENH: Draw new line when click is far from handle