Hotfix for JGraphXAdapterTest

Fixed .equals not working due to different classes
Constructor now throws IllegalArgumentException when called with null.
Extended JGraphXAdapterTest

Fixed unachievable tests
Separated genericTest
changed addJGraphTVertex and addJGraphTEdge from public to private.
Added load test for JGraphXAdapter
Formatting and cleanup of JGraphXAdapter
Added graph-constructor, updated jgraphx usage

Now using insertVertex/Edge instead of creating mxCell manually
Minor cleanup and tweak to JGraphXAdapterTest

100.000 edges/nodes ist too much
javadoc

gekürzt für sebi
Merge pull request #1 from SebiH/master

Updated JGraphXAdapter with more tests