Support building via autoconf and automake. mkfiles.pl now outputs a

Makefile.am, and there's a new mkauto.sh which builds a corresponding
configure script.

The old makefile has been renamed from 'Makefile' to 'Makefile.gtk',
indicating that the intended new _default_ approach is to use the
autoconf world. Makefile.gtk is provided as an emergency fallback in
case anything fails with the new stuff that used to work with it.

The new configure script does not support the same $(BINPREFIX) system
as the old Makefile did. However, as I understand it, it should be
possible to configure using --program-prefix="sgt-" (for example) and
then the binaries should all be renamed appropriately at install time.

The Makefile.am is quite painful. The Puzzles codebase relies heavily
on compiling individual object files multiple times with different the
cpp flags per build deliverable (program or library) and not per
source file. Solution: anything built with non-default compile options
has to go in its own little library. But that doesn't work either in
the general case, because as soon as you have more than one such
library linked into an application, Unix ld semantics bite you if the
objects in the libraries both refer to each other. So I ended up
building all those little libraries but not _using_ them - instead the
link commands for the programs needing those objects refer to the
objects directly, under the silly names that automake gives them.
(That's less fragile than it sounds, because it does _document_ the
names of the intermediate object files. But still, yuck.)

[originally from svn r9886]

configure.ac

@@ -0,0 +1,15 @@
+dnl Configure script for the Unix GTK build of puzzles.
+
+AC_INIT([puzzles], rNNNN, [anakin@pobox.com])
+AC_CONFIG_SRCDIR([midend.c])
+AM_INIT_AUTOMAKE([foreign])
+AC_PROG_CC
+if test "x$GCC" = "xyes"; then
+    : # FIXME: do something interesting enabling as many warning
+      # options as possible without breaking system headers.
+fi
+AM_PATH_GTK_2_0([2.0.0])
+AC_PROG_RANLIB
+AC_PROG_INSTALL
+AC_CONFIG_FILES([Makefile])
+AC_OUTPUT