facility to merge vertices
Merge branch 'g2o_hierarchical' of https://github.com/RainerKuemmerle/g2o into g2o_hierarchical
Merge branch 'g2o_hierarchical' of https://github.com/RainerKuemmerle/g2o into g2o_hierarchical
Merge branch 'g2o_hierarchical' of https://github.com/RainerKuemmerle/g2o into g2o_hierarchical
lil hack to parse also pure g2o files