Previously, 'configure' and its assorted machinery lived in the 'unix'
subdir, because that seemed like a clean place to keep it given that
all the other per-platform Makefiles live in their platform
directories. However, this never sat all that happily with autotools,
and even less so now that it likes to have object file pathnames
parallel source file pathnames: if you have Makefile.am refer to
source files outside its subdir as "../terminal.c" and enable
subdir-objects then any out-of-tree build calls the corresponding
object file "../terminal.o" and so your build products mostly end up
at the directory above your build dir! And as of autotools 1.14 my
previous compensatory bodge of prefixing every source file path in
Makefile.am with "$(srcdir)" has stopped working too.

So I'm giving in to necessity, and changing policy by moving the
configure machinery up to the top level of the source tree where
autotools will be less confused by it. This should not be taken as any
indication of the primacy of the Unix port, only of the recalcitrance
of autotools.

Whereas before we had a trivial script called 'configure' at the top
level that invoked unix/configure to effectively do an 'out-of-tree
build' (for make purposes) at the top level of the source tree, we now
have a similar script in unix/configure. So this _should_ make very
little difference: people who were previously running configure from
the top level should still be able to, and likewise people who were
running it from the unix subdir.

[originally from svn r10141]

mkfiles.pl no longer generates a Makefile.in, but instead generates a
Makefile.am on which mkauto.sh runs automake. This means that the
autoconfigured makefile now does build-time dependency tracking (a
standard feature of automake-generated makefiles), and is generally
more like what Unix people will expect.

Some of the old-style make command-line settings (VER=-DRELEASE=foo,
XFLAGS=-DDEBUG) will still work; the COMPAT settings are better done
by autoconfiguration, and my habitual 'XFLAGS="-g -O0"' for an easily
debuggable build will actually not work any more because CFLAGS is
specified _after_ XFLAGS, so I should instead write 'make CFLAGS=-O0'
(-g is the default in automake, removed at 'make install' time).

The new makefile will automatically degrade into one that builds the
command-line tools only, in the case where GTK could not be found. In
principle, therefore, it should be an adequate replacement for _both_
the static Unix makefiles, Makefile.gtk and Makefile.ux. I haven't
actually retired those in this commit, but I'm pretty tempted.

[originally from svn r9239]

autoconf/automake edifice, since my previous approach of guessing
its pathname turns out not to work on at least one kind of system.

[originally from svn r7984]

well as from outside.

[originally from svn r7963]

people who check the code out of Subversion can get it to go.

[originally from svn r5674]