altos: New telemetry report format (version 4). Supports tiny telemetry.

This completely replaces the version 3 format with a much simpler and
easier to parse scheme. It's described in detail in ao_telem.h, but
the basic idea is that the whole line is split into name/value pairs,
separated by whitespace. Every name is unique, and the values are
either strings or integers. No extraneous formatting or units are
provided.

Signed-off-by: Keith Packard <keithp@keithp.com>