recent Prefuse is not available via maven. this commit adds its source
as a module.

Prefuse is released under BSD. Original license and copyright in
license-prefuse.txt
move to a maven structure
javadoc fixed for java 8
javadoc fixed for java 8 (demost)
ignored files
override annotations added
override annotations added
dropped Lucene dependencies, more javadoc corrections
correct maven build to produce a valid Protege plugin
Merge pull request #3 from chiaradv/mavenbuild

Mavenbuild