Adjust changelog file (added ignore file .syignore)
Review Pim's IgnoredFiles; good
Structuring/begin code review + documentation DownOperation (and friends)
DatabaseReconciliator JavaDoc
Simplify DatabaseReconciliator (untested); add GitHub issue references to some TODOs
Refactor DatabaseReconciliator and DownOperation; move sync algorithm to reconciliator
DatabaseReconciliator JavaDoc cont'd
Merge branch 'develop' into feature/easyplugin