Implementing actions in the existing classes in Nova.

IMPORTANT: Sheduling won't work yet as there is no EnterStep defined yet in Nova, meaning the queue will never be created.
Adding AttributeUsage to our custom attributes.

We only want them to affect classes.
Created shell project

This will host the pages, which are needed for correct queue
implementation.
Fixing the progress indicator.
Removing useless method.
Created an ExtendedPage.
Documented the ExtendedPage.
Added enter/leave step logic.
Added closable tab control to allow sessions.
Added dynamic session management.

Improved Closable Tab Item logic.
Created a Closable Tab Control which generates Closable Tab Items.
rollback so we can pick up on this behaviour later on (e.g. for handling other things when closing a tab)
Preparing the layout for sessions.
Shouldn't have removed the optimizations.
Clean up sessions after removing them.

Changed the closable tab item logic so the event tunnels. This gives the parents a way to handle the event themselves.
Building the sessions layout.
Refactored Validation so we can use it without confusing it with the WPF validation class.

Small graphical tweaks for the tab item
Hidden the navigation of the used frames.
Allowing new sessions to be added through the control
Small tweaks
Fixed the sizing issue when tabs start overflowing.
Upgrade to .NET 4.5

- Also fixed state converter logic (check for errors before documents.
Errors will be null when no documents are open)
- Use session state rather than mainview state
- Normalize line endings.