Merge pull request #20 from jlothian/master

Change classnames, update and re-enable gtest unit testing, fix documentation generation via doxygen in Makefiles.  Fixes several make dependency issues and other small bugs.
Merge pull request #21 from jlothian/819da3520d2b650f51f1921876125f1e280d7b1f

Simplify I/O
Merge pull request #25 from jlothian/master

Adding recent feature work and bugfixes, support for OpenMP
Adding function to calculate k-core number of each node and overall graph degeneracy.
Merge branch 'upstream' into kcore-merge
Clean up new k-core code