* Added the example proof SumOfOnesFExampleProof to testing.scala. It is similar to the SumOfOnesExampleProof, but uses a recursive function f(0)=0, f(s(x)) = f(x) + s(0).
* Fixed typos in the Scaladoc in propositionalRules.scala

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1534 85d21ef8-add0-11de-ae77-5bfb9c5a3f34