First version of sections on color and exposure.
Fix rank filter kernels
Minor corrections
Wrap code at 80
Move the virtual framebuffer to top level yaml
CLN: Remove unused import and add module docstring
Merge pull request #1268 from pratapvardhan/morph-selem

Remove unused import and add module docstring
Merge pull request #1267 from blink1073/fix-travis-retry

Travis-CI: launch the virtual framebuffer from the top level yaml
Fix handling of imgnum
Fix handling of multi-image gifs and add test
Reinstate run_module_suite in test_pil
Fix file indexing in ImageCollection
Fix handling of singleton frames in pil_to_ndarray
Merge pull request #1263 from blink1073/fix-load-imgnum

Fix handling of img_num in PIL Plugin
Test all modules (including underscores), and always doctest
Use the test arguments from skimge.test_verbose
Update test args for command line
Do not use importlib in tifffile_local to avoid warnings
Improved docstring
Merge pull request #1269 from blink1073/test-all-modules

Test all modules (including those starting with underscores), and always doctest on Travis