Added new exampes Greatest_Common_Divisor and Euclid.
Added new exampes Greatest_Common_Divisor and Euclid.

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle