Rename UI elements involved with the bottom preview panel to use the
terminology "entry preview panel" instead of "details view" or "preview
panel". Change all associated variables, widgets, and classes to
reference EntryPreviewPanel. Create Config::upgrade() function and
deprecation mapping to help rename/remove previous config settings in a
clean manner.
Fixes#2327
* 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
