Fix errors in relabel_from_one docs; PEP8
Update snippets in notes to use double backticks
Fix doc string of warp functions
Fix various doc strings using the warp function
Merge pull request #740 from ahojnnes/warp-fix

Fix doc string of warp functions
Merge pull request #726 from jni/fix-relabel-doc

Fix errors in relabel_from_one docs; PEP8
ENH Faster perimeter computation

Measured a 30% speedup on a 640x640 image. Fundamentally, this makes
fewer passes over the image; so it should never be worse that the
previous implementation.
RFCT Simpler code for initializing array

Also, replaced skimage.measures.histogram by np.bincount.

Both changes were suggested in the pull request discussion by Juan
Nunez-Iglesias (jni):

https://github.com/scikit-image/scikit-image/pull/746
Merge pull request #746 from luispedro/master

ENH Faster perimeter computation