`tim` gets time units/more robust, `edplot` doc updates/refactor

The git log has more details, but besides a lot of improvement to edplot docs the headliner for this release is user-adjustable time units for tim (e.g. in your ~/.config/tim) via a string parameter -u=, --time-unit= which recognizes many well known time units that might be relevant. (Only up to "minutes" since you would not use tim for tests that individually take hours of real-time.)