* Add source folder keeshare for sharing with corresponding define WITH_XC_KEESHARE
* Move common crypto parts to src/crypto/ssh
* Extended OpenSSHKey
* Move filewatching to own file (currently in two related classes DelayedFileWatcher and BulkFileWatcher)
* Small improvements for style and code in several classes
* Sharing is secured using RSA-Keys which are generated on demand
* Publisher signs the container using their private key
* Client can verify the signed container and choose to decline an import,
import only once or trust the publisher and automatically import all
data of this source henceforth
* Integration of settings into Group-Settings, Database-Settings and Application-Settings
* Introduced dependency QuaZip as dependency to allow combined export of
key container and the (custom format) certificate
* Create history-based merging that keeps older data in history instead of discarding or deleting it
* Extract merge logic into the Merger class
* Allows special merge behavior
* Improve handling of deletion and changes on groups
* Enable basic change tracking while merging
* Prevent unintended timestamp changes while merging
* Handle differences in timestamp precision
* Introduce comparison operators to allow for more sophisticated comparisons (ignore special properties, ...)
* Introduce Clock class to handle datetime across the app
Merge Strategies:
* Default (use inherited/fallback method)
* Duplicate (duplicate conflicting nodes, apply all deletions)
* KeepLocal (use local values, but apply all deletions)
* KeepRemote (use remote values, but apply all deletions)
* KeepNewer (merge history only)
* Synchronize (merge history, newest value stays on top, apply all deletions)
