Add `VertexConnectivity` #235

Job	Run time
--enable-debug --enable-compile-warnings --without-intrinsics	3m 24s
--with-external-bliss --with-external-planarity	4m 56s
--enable-debug --enable-compile-warnings	3m 16s
--enable-compile-warnings --without-intrinsics	3m 39s
--with-external-planarity	4m 45s
--enable-compile-warnings	3m 22s
--with-external-bliss	4m 58s
--enable-debug --without-intrinsics	3m 18s
--enable-debug	3m 24s
--without-intrinsics	3m 24s
	38m 26s

Provide feedback