A number of small script fixes/tweaks from usage

- Fixed prettyasserts.py parsing when '->' is in expr

- Made prettyasserts.py failures not crash (yay dynamic typing)

- Fixed the initial state of the emubd disk file to match the internal
  state in RAM

- Fixed true/false getting changed to True/False in test.py/bench.py
  defines

- Fixed accidental substring matching in plot.py's --by comparison

- Fixed a missed LFS_BLOCk_CYCLES in test_superblocks.toml that was
  missed

- Changed test.py/bench.py -v to only show commands being run

  Including the test output is still possible with test.py -v -O-, making
  the implicit inclusion redundant and noisy.

- Added license comments to bench_runner/test_runner

scripts/plot.py

@@ -535,7 +535,7 @@ def datasets(results, by=None, x=None, y=None, define=[]):
                     results,
                     x_,
                     y_,
-                    [(by_, k_) for by_, k_ in zip(by, ks_)]
+                    [(by_, {k_}) for by_, k_ in zip(by, ks_)]
                         if by is not None else [])
 
     return datasets