Resolve "Bug when writing a measurement file with no GW file input"

Closes #103 (closed)

• Test measurement-file writing
• Cleanup test measurement file after tests
• Set gw_group to None when no GW file are used as inputs

changed milestone to %v1.2

added bug label

added 3 commits

• 89cd9f40 - Setting `gw_group` to None when no GW file are used
• 192dc544 - Add writing measurement files to tests
• fec6b55e - Cleanup measurement file after tests

Compare with previous version

changed the description

requested review from @hinchaus

marked this merge request as ready

approved this merge request

merged

mentioned in commit 1f895a5b