Update WebP from 0.4.0 to 0.4.1
Make WebP with 4 job slots - ~2.4 times faster
Make OpenJPEG with 4 job slots - ~2.2 times faster
Make OpenJPEG with 4 job slots - ~2.2 times faster (take 2)
backup implementation of Round for windows platforms
mp is a little twitchy on windows
allowing for libwebp* library names
Merge pull request #871 from wiredfool/windows_fixes2

Windows fixes
Update CHANGES.rst [CI skip]
Merge pull request #864 from hugovk/make-j

Update WebP and build it and OpenJPEG with 4 job slots
Refactor inheritance tree of test_file_libtiff_small
Merge pull request #872 from wiredfool/test_libtiff_inheritance

Refactor inheritance tree of test_file_libtiff_small
Additional dependencies [ci skip]