* Rewrite the backend manager.
This creates a new more logic backend manager that handles all backend operations.
For each top-level operation, there is now a single backend manager instance that is passed to sub-commands.
The internals of the backend manager are now rewritten to use async logic instead of threading.
The design uses a single task runner that dispatches operations and honors concurrent settings and limits from one place.
The logic for each operation has been moved into a separate files/classes to make it easier to understand each operation.
This fixes#5804
* Fixed a few issues with not awaiting tasks
* Fixed not creating empty databases
* Fixed an issue with hashes not being recorded on download
* Reworked the download logic to avoid attempting to decrypt the file if it has been modified.
* Review fixes
* Renamed db collector to better reflect the purpose.
* Review fixes
The PurgeFilesHandler begins new transactions using the same database
connection. During a dry-run, these transactions are rolled back, and a
subsequent attempt to rollback in the PurgeBrokenFilesHandler then
resulted in an exception.
To avoid this, we perform the rollback in the PurgeBrokenFilesHandler as
soon as we can.
I'm not entirely confident that this is the correct fix, but it appears
to resolve issue #4379.
This fixes#4379.
Changed a few things on the way, removing the log process
# Conflicts:
# Duplicati/Library/Main/Controller.cs
# Duplicati/Library/Main/Database/ExtensionMethods.cs
# Duplicati/Library/Main/Database/LocalBackupDatabase.cs
# Duplicati/Library/Main/Duplicati.Library.Main.csproj
# Duplicati/Library/Main/Operation/BackupHandler.cs
# Duplicati/Library/Main/Operation/FilelistProcessor.cs
# Duplicati/Library/Main/Operation/PurgeBrokenFilesHandler.cs
# Duplicati/Library/Main/Operation/TestFilterHandler.cs
# Duplicati/Library/Main/Options.cs
# Duplicati/Library/Main/ResultClasses.cs
# Duplicati/UnitTest/BasicSetupHelper.cs
# Conflicts:
# Duplicati/Library/Main/Controller.cs
# Duplicati/Library/Main/Database/ExtensionMethods.cs
# Duplicati/Library/Main/Database/LocalBackupDatabase.cs
# Duplicati/Library/Main/Duplicati.Library.Main.csproj
# Duplicati/Library/Main/Operation/BackupHandler.cs
# Duplicati/Library/Main/Operation/RecreateDatabaseHandler.cs
# Duplicati/Library/Main/ResultClasses.cs
First attempt at merging all changes from 2016-10-08 to now :/
