Version 0.2.1

This release includes two major performance improvements to the sparse-direct LDL factorizations and DPP sampling: (1) Simplicial, up-looking factorizations are now automatically used for small and/or low-intensity factorizations, leading to orders of magnitude speedups on some matrices, and (2) Nested OpenMP tasking now terminates based upon the workload of the subtree rather than its depth. Beyond the performance improvements, the factorizations and DPP sampling can now be instrumented -- via the -Denable_timers=true configuration option -- to output a Graphviz visualization of the inclusive and exclusive processing times at the top of the supernodal assembly tree. And an example driver was added to visualize -- via ASCII and/or TIFF -- uniform and/or maximum likelihood spanning trees from Z^3 or a hexagonal tiling of the plane.