#18 Provide zipped / jarred src

[nlang]

Currently, file releases only contain class files. This is a
good thing, as the distribution size is minimized in this
manner. For debugging purposes, however, a jar/zip
containing all sources would be really helpful. I suggest
to provide one zip/jar file per release containing the
source only. This file can then easily be added
as 'source attachment' in the Eclipse IDE.