Introduce, and implement as usefully as I can in all front ends, a

Introduce, and implement as usefully as I can in all front ends, a
new function in the drawing API which permits the display of text
from outside basic ASCII. A fallback mechanism is provided so that
puzzles can give a list of strings they'd like to display in order
of preference and the system will return the best one it can manage;
puzzles are required to cope with ASCII-only front ends.

[originally from svn r8793]