Use ax_pkg_swig.m4 from the GNU Autoconf Macro Archive as it is actively
maintained and update configure.ac accordingly.
Moved the Swig test to the bindings section of configure.ac.
Refactored the logic of the Swig test.
Updated ax_python_devel.m4 to latest version in the Autoconf Macro
Archive (removes two email addresses, not other changes).
Removed aclocal-include.m4 and lf_warnings.m4 as they were not being
used any longer.
Update macros definitions in macros/Makefile.am to recent additions and
deletion of the local macro files.
Nate Bargmann