Add relabel_sequential, deprecate relabel_from_one
Add relabel_sequential to __init__ import
Add new tests for relabel_sequential
Remove deprecated use of relabel_from_one
Rename deprecated relabel_from_one in docstring example
Only raise umfpack warning if cg mode is used
Monkey-patch UmfpackContext __del__

By putting the failing statement in a try: except: clause, the
exception is caught and the error message is silenced.

See
https://groups.google.com/d/msg/scikit-image/FrM5IGP6wh4/1hp-FtVZmfcJ
and
http://stackoverflow.com/questions/13977970/ignore-exceptions-printed-to-stderr-in-del/13977992?noredirect=1#comment28386412_13977992
Merge pull request #755 from jni/rename-relabel

Rename `relabel_from_one`
Merge pull request #709 from sciunto/wu

Wu's anti-aliased circle + aa line + bezier curve + unittest
Remove unused imports in random_walker source
Add comment and links explaining Umfpack import
ENH: optimized label2rgb()
Deprecate default mode 'bf' in random_walker
Add change in random_walker default mode to TODO
Update SLIC in example to most recent interface

SLIC has been updated a few times since this example was created,
adding support for grayscale images (so converting to RGB is no longer
necessary) and changing the keyword "ratio" to "compactness". This
commit brings the example up to date.
fixed error in label2rgb() when label is a binary array
Merge pull request #762 from jni/update-slic-example

Update SLIC in example to most recent interface
handle case when there are no labels
Merge pull request #761 from kemaleren/optimized_colorlabel

color.label2rgb() is much faster.
Fix join_segmentations example using img_as_float

data.coins() returns a ubyte image in Python 2.7.x but a float32 image
in Python 3.x. This ensures that the image always has the same type for
the rest of the example.