Improvements to optimisation tests of the test suite.
These improvements include all of the suggestions by Chris MacRaild at
https://mail.gna.org/public/relax-devel/2006-10/msg00141.html (Message-id:
<1161860754.3525.27.camel@...>).
The exact changes are detailed in the follow up post located at
https://mail.gna.org/public/relax-devel/2006-10/msg00145.html (Message-id:
<7f080ed10610260854p3d7d0a45w32c731345ed244d3@...>).
