Loss latent models

Contains a framework for defaultable baskets metrics models. Most current code is centered on latent models and cash baskets. Future developments include counterparty positions baskets and bonds. See wiki in progress. Latent models can be integrated or simulated.

Apologies for the large PR but I wanted it to be stable. There is still quite a few additions to come in the future. Most code is to lie in the experimental section. Some of the previous code which is to become redundant is left there to await for discussions/input from the rest of the group. Test cases use the new code.

The functionality can also be tested with the add-in addition in branch 
https://github.com/japari/quantlib/tree/LatentQLXL

Forgot to mention, theres only VC9 project files for windows.
The two test cases above take 6 minutes each on my machine. This file alone uses up about 40% of the whole test suite. Would it be possible to decrease precision, or reduce the execution time in some other way, and still have a meaningful test?