configury: use ./bootstrap && ./configure && make & sudo make install.

* bootstrap: New file, from Libtool master HEAD.
* bootstrap.conf: New file.  Configure bootstrap for Specl.
* build-aux/gitlog-to-changelog: New file.  Required for
'make dist'.
* configure.ac: New file. Check Specl build prerequisites.
* m4/ax_compare_version.m4, m4/ax_lua.m4, m4/ax_with_prog.m4:
New files. Used by configure.ac.
* src/version.lua.in: New file.  Configured constants.
* specl: Moved from here...
* specl.in: ...to here.  Rework to use src/version.lua.in.
* Makefile.am: New file. Top-level non-recursive Makefile.
* src/specl.mk: New file. Make fragment for specl directory.
* .gitignore, build-aux/.gitignore, src/.gitignore: New files.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
specs: specl specs for specl.

* src/specl.mk (check-local): Run specs with 'make check'.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>