Merge pull request #318 from Garyfallidis/render_installation

Corrected some rendering problems with the installation instructions
Updated Changelog and announcements
initial structure
NF: cython file added for the denoising module
raw algorithm done
NF: added function for fast nlmeans. More debugging is needed
Still debugging this
Added padding
Changed function name
Still debugging...
padding added
BF: added another check for dividing by zero
Removed gil prints
Investigating correct boundary regions
For some reason it smooths too much the image. Still investigating
TEST: adding tests for denoising
BF: corrected stepping
changed patch and block size
fixed overblur
fixed oversmoothing