Add serialization for per-user solution settings
Adding code to get solution location and storing the settings
Can now read/write outline settings (first attempt)
Adding new tests for OutlineSettings and refactoring code
Adding OUtlineSettings.Save test
use lowercase on file settings to avoid issues
Refactor user settings persistence code to allow for options other than a file next to the solution file.
Store user-specific settings in SUO file instead.
Merge branch 'slnsettings' into develop