Reduced memory parameter of unit tests to 2G.

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@990 48fcbb9e-5639-0410-8b25-842128a4905d
When an LMM does not have a specific discount curve, the corresponding curve is calculated from the forward curve and returned.

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@991 48fcbb9e-5639-0410-8b25-842128a4905d
Improved analytic swaption approximation under OIS discounting. Some code clean up.

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@992 48fcbb9e-5639-0410-8b25-842128a4905d