Adding a basic property system with support for strongly types properties with custom parsing logic.
Adding some additional configuration goo, including concrete implementations of the typed property system and some concrete PropertyHandlers, in the form of CommonProperties, SourceControlProperties, IndexProperties and SearchProperties.  The latter two don't hold anything yet, and so do not have unit tests.  Once we start adding in access to tuning parameters, they can go in those two classes and unit tests may become useful.
The next round of changes.