DOC : removed line about un-needed dependencies in Windows

We no longer bundle `dateutil` or `pyparsing`.
colors: Replace docstring ''' with """
test_colors: Fix typo
colors: Add power-law normalization
power_norm_demo: Initial commit
hist2d: Add a note mentioning PowerNorm
Radius fix in _path.cpp

Updated the points_in_path method to allow negative radii as is implied by the documentation.
BUG: Removes iteration over locals (no-no) in mathtext
Added test for negative radius in Path.contains_points
Added point which is inside the unit circle but not inside a circle of radius 0.5
BUG: Fixed bug in handling drawing bitmap images accounting for the device scaling
DOC : added missing doc changes from #2844
CLN : removed version check that required numpy > 1.2
Merge pull request #2848 from tacaswell/windows_install_doc

DOC : removed line about un-needed dependencies in Windows
Merge pull request #2949 from tacaswell/np_version_purge

CLN : removed version check that required numpy > 1.2
Merge pull request #2939 from cimarronm/macosx_device_scale

Fixes a bug in drawing bitmap images in the macosx backend for handling device scaling
Merge pull request #2915 from simongibbons/master

Consistency of the radius argument for Path.points_in_path
Merge pull request #2926 from cimarronm/mathtext_remove_locals_iter

BUG: Removes iteration over locals (no-no) in mathtext
PEP8 : add missing line to un-break build
Fixed issues with errorbar limits