Glymur

Qualify support on Python 3.9, OpenJPEG 2.4
Add support for multithreaded writes

Update setup.py to include tests
Update gdal imports to stop DeprecationWarning

Remove GDAL from setup.py requirements

Removed support for python2.7
Fixed Cygwin support
Fixed appveyor builds, Travis-CI framework reworked
Some fragile tests removed

Qualify on Python 3.8

Fix geotiff UUID corner coordinate string representation
Improve warning and error messages
Correct improperly raised exception types
Remove build/test for Python 3.4 (EOL)
Fix read-the-docs requirements