[build] Remove unused files
[build] Cleanup the scripts directory
[engine] Make “largeop” synonym to “stretchy”

Not sure if we should treat large operators like TeX does (i.e. only
having two sizes, display and text), but this should restore the old
behaviour for now.

Fixes #17.
[engine] Simplify a bit
[backend] Fix stretching in both directions

If we are stretching an operator in both direction, the horizontal
stretching ends up discarding the result of the vertical stretching that
preceded it.

This fixes #16 as a side effect, though I think there is something else
wrong there, as we should’t be stretching horizontally to begin with.
[engine] Avoid requesting stretch needlessly

Don’t try to fix the value of the stretch if no stretch is requested,
otherwise we might end up trying to horizontally stretch stretchy
operators that has non-zero lspace or rspace because of the difference
between the natural width and the spaced one.

Related to #16.
Minor

Too much noise.
[engine] Typos!

From 806ab13.
[config] Remove the local dictionary

The history of those entries is lost, but they look dubious, so lets
stick to what the standard defines.
[engine] Load the operator dictionary during build

We no longer need to parse the XML directly, it is all compile-in now.

First part of #14.
[view] Stop loading operator dictionary from file

Fixes #14.
[config] Remove unused DTD
[config] Drop configuration support
[build] Fix after a67cc51
[gtk viwer] Use bigger font size by default
[build] Remove unused M4 file
[doc] Remove ChangeLog that is never updated
[doc] Fix and build the Texinfo documentation

Mostly outdated, but just in case I get around updating it.
[build] Don’t keep m4 dir under version control

I did so to silence an aclocal warning, but it is just a warning, so
just don’t bother.
[doc] Move some doc files to doc/