* 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
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 :/
