Sun Dec 2 11:55:17 EST 2018

Makefile and guard deps

1. Using stamps, initial builds will not have dependency issues.

2. Guard deps are only intended for incremental builds, so they need
   to be "correct enough" wrt. the changes made by the developer.

The bottom line is that:

- Single Makefile is preferred, but not always possible.  Try at least
  to make these cover as much ground as possible.

- When recursive make is needed, try at least to get the guard
  dependencies right, and use time stamps.

If there is even a single phony target, the entire build is now
infected and becomes "idempotent impreative" instead of "dataflow".