* Refactor Lightbeam's tests. This refactors Lightbeam's tests.rs file into several pieces, separating quickcheck tests into their own file, and moving tests which can be run as wast tests into `tests/misc_testsuite`, and creating a tests directory for the rest. * Remove the old filetests tests. These are all covered by misc_testsuite and spec_testsuite tests. * rustfmt * Remove the "bench" feature.