add example script for polygon approximation
remove unused import and code from polygon approximation example
remove colons in comments
make loop condition more readable
improved polygon approximation example script

made existing example parameters more readable and add another example with
a more complex shape based on a subdivision algorithm.
add subdivision of polygonal curves using B-Splines
add note about size if resulting polygonal curves
update polygon example with subdivision
add test case for subdivision of polygons
add some more comments to subdivision of polygons code
make subdivision mask code more readable und debuggable
fix wrong parameter name in doc string
add test case for non-circular subdivision of polygons
Add possibility to preserve ends and update tests
Update subdivision example with preserve_ends parameter
Merge pull request #250 from ahojnnes/approx-polygon

ENH: Add polygon approximation and subdivision.
Merge pull request #258 from tonysyu/imshow-filename

ENH: Allow imshow to show images when given file name.
BUG: Remove print statement that caused py3 tests to fail.
Add support for boolean dtype conversion
Update test cases for boolean dtype conversion