eval the critical parts. Use specific exit codes. Add --run-time, --progress, --continue-on-error, and --defaults-file. Uncomment the version check call. Update the docs.

t/pt-upgrade/diff_query_times.t

@@ -46,6 +46,12 @@ test_diff_query_times(
    expect => undef,
 );
 
+test_diff_query_times(
+   t1     => 0.01,
+   t2     => 0.5,
+   expect => ['0.01', '0.5', '50.0'],
+);
+
 test_diff_query_times(
    t1     => 23,
    t2     => 82,