baseline-referenced text/markups?

[Kieren MacMillan]

Hello all,

What would be involved in changing the “reference point” of markups to be the 
baseline (instead of whatever the heck it is now)?

The many unfortunate things demonstrated in the following “default”** snippet 
keep me up at night (figuratively *and* literally):

\version "2.17"

\layout { system-count = 1 }

music = {
  \markLengthOn
  \mark \default \tempo "No descenders." R1
  \mark \default \tempo "No descenders." R1
  \mark \default \tempo "going going going." R1
}

\new Staff \music

Thanks,
Kieren.

** the only non-default is the \markLengthOn… which really *should also* be a 
default!!