Saving workspace functionality

Saving workspace functionality:
- the Dynamo receives a message about saving, saves all workspaces as files and sends them back to the Flood.

Part of changes that had to be uploaded with "Changing the way of geometry transmission" but wasn't:
- receiving a geometry message, process it and send back the geometry data

Enhancements of the code (there is not a lot of them, so I add them into this PR):
- checking for not null, correct guid, removing old code, etc
Sounds good, could you please add a ```///``` comment on both ```CreatingName``` and ```DisplayedName```? That will help whoever looks at the code in the future without seeing this PR. Also, please rename ```DisplayedName``` as ```DisplayName``` (which is more commonly adopted).

Also please create a new YouTrack task for renaming ```CreatingName``` to ```CreationName```, that can be done separately in another PR in future.