Gstreamer 1.0: merge !9 into gstreamer_python_upgrade
Related to #56 (closed)
This is a larger merge, and I've not thoroughly checked each merge conflict (relying a little on remembering where issues where in !63 (closed)), but I've done 2 runs:
/fred/oz996/tdavies/spiir_project/sources/testing/gout/py3/MR67_tests
They both ran to completion, have the usual ND in results, and 'appropriate' file sizes (background files were reduced in size as expected)
As before, to check these changes you'd probably have to check these changes against the original changes (see !9 (diffs)). Note the commits I merged have a different hash, since they were cherry picked in !25 (merged).