Support for Java 1.5?

[mkorpela]

Seems like there is no support for Java 1.5 anymore.
At least String.isEmpty() method that is used here and there in the source code is not working with Java 1.5..
We should decide if this is still needed.

[mkorpela]

Actually seems like the task for supporting Java 1.5 completely might be too complex.
The initial tests are not promising although SwingLibrary can now more or less be somewhat used with Java 1.5.