Redmine#5342: rename VersionCheckSchedulePackage to WillSchedulePackageOperation and document it
Redmine#5342: document and simplify VerifyPromisedPatch
Redmine#5342: document and simplify VerifyPromisedPackage
Redmine#5342: document and move InvalidateSoftwareCache
Redmine#5342: document ExecuteSchedule
Redmine#5342: document ExecutePatch, ExecutePackageSchedule, ExecuteScheduledPackages
Redmine#5342: add brief doc on overall structure of verify_packages.c
Redmine#5342: undo simplify VerifyPromisedPackage
Redmine#5342: test non-filebased repo