Automatically abbreviating names of all the different things that are
displayed on a map is much easier with names spelt out in full in the
input data, than expanding those names if they were provided in an
abbreviated form.  This is basically why OpenStreetMap raw data contains
mostly full names even if they're rarely / never written that way,
and only pronounced that way.  Expansion may be ambiguous so there's
no good way of automating it, especially taking l10n into account.

However when rendering graphical maps it may be useful to still show
abbreviated names, particularly in places and scales where the
map is crowded with labels.  So the code to do that abbreviation
automatically needs to be part of the rendering toolchain.  That
code may still be useful in other projects, so it is abstracted out
here as small set of C functions that can hopefully be re-used.

It focuses on the type of names that are seen in cartography and
trying to expand it to cover other common abbreviations may make
it either much more complex, or more false-positives prone.  So
perhaps it's better for it to stay focused on this one task,
which it turns out isn't completely trivial.