weekly release 1.9.19+
MDL-37672 Always include gradebook categories in bacukp
MDL-38225 - data: Database entries are now linked correctly.

This was a regression that was fixed in the 2.x versions but not 1.9
Merge remote branch 'origin/MOODLE_19_STABLE' into LAE_174
Merge remote branch 'appstate/MDL-37672' into LAE_174
Updated LAE_readme for 1.9.19+LAE1.7.4 release.