map-dhcp-02 as submitted to IETF
(manual merge from https://github.com/wdec/MAP)
Updated example from previous version merged
- port parameters option should not go into MAP Rule option, but in
  the container option. That makes the whole structure flatter (just
  one level of nesting, instead of two)
- recalculated lengths to reflect that
- added text that describe how options are nested
- removed option diagrams. Repeating them in examples section didn't
  add any value and made reading the whole text slightly more difficult
  to read.