Made KTExtensibleStructCore a doubly-linked list, with Next, Prev, Last and First functions.
Updated KTData and KTCut to work with the new extensible struct setup.
Added TestCut validation program
Debugging cuts and how they're used in data.
Fixed AddCutResult overloading
Cut and extensible struct factory debugging.  They seem to be functioning now.
Made KTCut configurable