Support for Cray!

With thanks to @rouson, @MatthewHambley, and others at Cray, pFunit now supports the Cray compiler on the master branch.

Please note that this latest release has not been tested with older compilers and may therefore not have backwards compatibility. I'm also seeing a panic with NAG, but hopefully the user community is not dependent on support there. I will look into it, but only fix if it is relatively simple or exposes a real bug in the pFUnit source.

CMake bug fix

Fixed #12.