Cleanup and improvements to CPController

After examining the code, the so-called "newer style of context matching" is never used -- and even if the corresponding user default for "AllowMultipleActiveContexts" would be enabled, it cannot do anything really useful with the current implementation and logic anyways. I guess that that "new style" is actually something coming from older developments that have never been completed. (Or is that something planned for CP 3.0?)

Dustin, any comments on that unused mode? Any objections to deleting the branch for it?

Also, the change makes a cleanup inside method **guessMeetsConfidenceRequirement**. Removing the commented code (and some uncommented -- but unused -- fragments related to it) for a no-guess situation, which is handled in a very different part of code now. Plus some optimizations to the remaining code are also applied.

Let me know if you have any questions or concerns.