Added methods/code to create time-shifted models.

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@781 48fcbb9e-5639-0410-8b25-842128a4905d
Added stochastic versions of some analytic formulas.

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@782 48fcbb9e-5639-0410-8b25-842128a4905d