fix import problems
remove no-longer-needed file

as it looks, this has already been converted to a set of related
pages. So we can remove the (old) original file.
improve $ActionExecOnlyOnceInterval documentation and samples

most importantly, point out that it must be re-set to not affect
other actions.
Merge branch 'v5-stable' into v7-stable
Merge branch 'v7-stable' into v8-stable

Conflicts:
	source/configuration/modules.rst