Code generation saved files even when they had not changed, which often caused code generation cascades. So, don't save files unless they have changed.
Use rsync to determine which files have changed since the last test run. The manifest of changed files is saved and not removed until all code generation and builds have completed. If an error occurs the work will be redone on the next run.
The eventual goal is to do all the builds from the test/repo directory created by rsync but for now it is only used to track changes.
Low-level functions only include stack trace in test builds while higher-level functions ship with stack trace built-in. Stack traces include all parameters passed to the function but production builds only create the parameter list when the log level is set high enough, i.e. debug or trace depending on the function.
Now only two types of locks can be taken: archive and backup. Most commands use one or the other but the stanza-* commands acquire both locks. This provides better protection than the old command-based locking scheme.
This implementation should be faster because it does not stat each file. It simply assumes that most directory entries are files so attempts an unlink() first. If the entry is reported by error codes to be a directory then it attempts an rmdir().
