Compatibility with Java5 : Matrex 1.3.01

I published a new release of Matrex, 1.3.01, to cope with the fact that Matrex 1.3 was able to run with Java6, but not with Java5.
The problem was a call to the String.isEmpty() method, which is only available from Java6.
In 1.3.01 this call has been replaced and this version has been tested with Java5.

Thanks to Braxton who found the problem.