Keep at least 2 backups and any created within an hour
Disable integrity manifest writing
Tweak var names
Merge pull request #684 from sstephenson/keep-recent-backups

Keep recent backups within a time window
Remove unused var
Allow new instances of DirectiveProcessor
Use correct comment style
Allow directive processor comment style to be configured

Closes #674
Cache singleton instances
Merge branch 'master' into 4.x