#239 With empty classpath process cannot start

[Björn Kautler]

When not specifying a classpath, or when specifying a pattern like lib/*.jar and it does not find any matches, the built commandline contains the -classpath parameter with a single double-quote as argument which fails to start.

As a work-around, a dummy entry that does not contain wildcards can be specified as non-existing classpath entries are ignored by the JRE as per the Java spec.