[maven-release-plugin] prepare release finmath-lib-1.2.20

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@1158 48fcbb9e-5639-0410-8b25-842128a4905d
[maven-release-plugin] prepare for next development iteration

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@1160 48fcbb9e-5639-0410-8b25-842128a4905d
Added reference to project documentation.

git-svn-id: http://svn.finmath.net/finmath%20lib/trunk@1161 48fcbb9e-5639-0410-8b25-842128a4905d