Fixes bug with implementation which caused check to happen more often
than required. Noticed because failed on case where two nodes to find lca
for were same, so added new test to that effect. At same time noticed that
some test cases were for dags, not trees, so removed those as only pass by luck
Revered formatting back to what it used to be
Merge pull request #71 from leocrawford/master

Fix problem with TarjanLca implementation
Credits for last commit.
Merge branch 'master' of https://github.com/jgrapht/jgrapht