Added recipe for icalendar-3.8.4 package
Detect binary prefix files in tk
Update to tcltk 8.5.17
Merge branch 'master' of github.com:pydata/conda-recipes
Fix tcltk downloading
Keep trying to fix the tcltk downloading
Compile nlopt as a shared library
Update flake8
ENH Add mahotas, imread, and libwebp recipes

These have been tested separately at
https://github.com/luispedro/mahotas-conda
https://github.com/luispedro/imread-conda
https://github.com/luispedro/libwebp-conda