Rename TOPDIR to TOPSRC, can't get around requiring it and it's more
descriptive this way anyway. Also, revert the use of the m4_esyscmd()
macro in configure. It's kinda cool, but I'll come up with a better way
to do it.
We need to figure out a way to make docs in unusual places, like in the
SourceForge shell environment -- which doesn't have an extremely recent
autotools. This is an extremely stripped-down automake/autoconf setup that
provides the bare minimum needed to AC_SUBST variables.
It's dirty and hacky, but it kinda works.
