BUG FIX - NewMetadata MUST return nil on missing files.

Commit a4b336bdba243cf6163073492ef51582aa58542e removed unused fields
from Metadata struct and, incorrectly, a critical error handling path
that ensures NewMetadata returns nil for a non-existent file.

This change passed tests because the tests depend on a manually created
binary. To avoid this class of errors, the tests MUST rebuild the
binary anew.
obsolete file
Add rename and alias do scripts

Renamed .do scripts to shorter shell scripts without the standard
prefix or suffix. They are called more often as shell scripts,
which don't depend on a working redo, than as do scripts.
Each renamed .do script now invokes its eponymous script.