Use SPDX license identifier and set all files to GLP3+ to be consistent with...

Use SPDX license identifier and set all files to GLP3+ to be consistent with license headers in the source files. Excluded tests from being installed via 'pip install'. Set development status to 'stable'. Updated version info.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>
3 jobs for v0.18.6 in 10 minutes and 1 second (queued for 61 minutes and 37 seconds)
latest