1 - Move temp directory name into local test config.
3 - Add --show-unsupported, don't show by default?
5 - Finish documentation.
7 - Optionally use multiprocessing.
9 - Support llvmc and ocaml tests.
11 - Support valgrind in all configs, and LLVM style valgrind.
13 - Provide test suite config for running unit tests.
15 - Support a timeout / ulimit.
17 - Support "disabling" tests? The advantage of making this distinct from XFAIL
18 is it makes it more obvious that it is a temporary measure (and lit can put
19 in a separate category).