This change moves the RADIX_TYPE enum into its own header. This resolves a compilation error and reduces the dependency graph by allowing RadixToStringConverter to include just the enum header rather than the entire CalcEngine header.
Change verified by ensuring Calculator build locally.
Calculator (the main app project) depends on CalcManager, but only transitively: Calculator -> CalcViewModel -> CalcManager.
However, Calculator's project file currently has a direct dependency on CalcManager. Let's remove this to make it harder to accidentally introduce new dependencies between the layers.
Also cleaning up some commented-out directives in the CalcManager MSBuild file.
A few small changes to improve the view of the code in Solution Explorer:
* Delete folders from solution explorer which don't appear on disk (Resource Files, PerfTrack)
* Delete files on disk which aren't compiled into the project (Type.xaml)
* Rename CalculatorHistory.Cpp to CalculatorHistory.cpp, for consistency with other files
