Fix some Landscape.io errors and warnings
fix bicubic stretch interpolation
unlock upscale filters
convert tabs to spaces
Add tests. Rise for "P" and "1".
Merge remote-tracking branch 'upstream/master' into landscape-fixes
Don't use builtin as variable
Merge pull request #970 from homm/fix-bicubic-stretch

Fix bicubic stretch interpolation
Update CHANGES.rst [ci skip]
Make test_imaging_stretch.py runnable as a standalone script
Fork from master and send pull requests to master

Master is essentially our dev branch.

[CI skip]
Merge pull request #992 from hugovk/testimagingstretch

Make test_imaging_stretch.py runnable as a standalone script
Merge pull request #984 from hugovk/landscape-fixes

Fixed duplicate imports, naming variables after builtins