Added graph and graph plotting functionality.
Merge branch 'master' of https://github.com/darpa-xdata/xlang
Merge branch 'master' of https://github.com/darpa-xdata/xlang
Merge branch 'master' of https://github.com/darpa-xdata/xlang
Merge branch 'master' of https://github.com/darpa-xdata/xlang
Merge branch 'master' of https://github.com/darpa-xdata/xlang
Merge branch 'master' of https://github.com/darpa-xdata/xlang
Merge branch 'master' of https://github.com/darpa-xdata/xlang
Added a SNAP importer and png writer for graphs.
A minimal sufficient example for graph clustering using R from C.
Changed calls of "require" to "library".