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.
Using .NET 4.5's CallerMember attribute

This happens at compile time so is a serious upgrade in speed from the
expression tree caller and far more user friendly than the string typed
caller (which can still be used!)
Adding WindowChrome

Since it's implimented in .NET now.
Created resource files instead of strings.
Should be protected, not protected internal.
Refactor

- Improved page creation
- Removed InternalsVisible
- Improved Session handling