Perf tests

This pull request adds performance tests to the test suite using the ctest structure.  Part of this includes a re-structuring of the test directories to test_regression and test_performance, and renames tests so that a specific test suite can be run with the -R flag to ctests.

PR is incomplete until a larger spread of performance tests is added.

- [x] Restructure test directories
- [x] Set up test timing structure
- [ ] Finish adding full coverage of tests as described in #230