Check expat with pkg-config and enable XML reading support by default.
Bump minimum autoconf version required to 2.69 (for the AC_CHECK_HEADER_STDBOOL macro)
Remove autogen.sh, just use autoreconf -i
Remove the --disable-xml from travis configuration
Update autoconf to 2.69 in CI servers
Update expat to 2.1 in CI servers (provides pkg-config support)
Merge pull request #71 from fdelapena/master

Enable expat by default in autotools