Extensions to deegree and multi language support

[tfr42]

Accepting PR containing source codes besides Java source codes.

TMC shall accept PR which contain accepted source codes as documented in https://github.com/deegree/deegree3/wiki/Multi-language-support

• Requires improved build system with multi language support

[tfr42]

see also https://www.deegree.org/blog/blog-quo-vadis-deegree/

[tfr42]

From last TMC meeting (https://github.com/deegree/deegree3/wiki/tmc-meeting-minutes-201905249):
The project is committed to the JVM and shall focus on Java source code but might accept other languages which compile to Java byte code executable on the JVM.
The issues with JNI is that extensions are not as easy to deploy.
Optional modules can make use of JNI but for core functions JNI shall not be used.