bump version to 0.9.19, extra warnings

Bump version to 0.9.19; add some extra warnings (using some new m4 macros)

configure.ac

@@ -1,4 +1,4 @@
-## Copyright (C) 2008-2015 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+## Copyright (C) 2008-2016 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ##
 ## This program is free software; you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -14,13 +14,20 @@
 ## along with this program; if not, write to the Free Software Foundation,
 ## Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
-AC_INIT([mu],[0.9.18],[https://github.com/djcb/mu/issues],[mu])
+AC_PREREQ([2.69])
+AC_INIT([mu],[0.9.19],[https://github.com/djcb/mu/issues],[mu])
+AC_COPYRIGHT([Copyright (C) 2008-2016 Dirk-Jan C. Binnema])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_SRCDIR([mu/mu.cc])
 # libtoolize wants to put some stuff in here; if you have an old
 # autotools/libtool setup. you can try to comment this out
 AC_CONFIG_MACRO_DIR([m4])
-AM_INIT_AUTOMAKE
+AC_CONFIG_AUX_DIR([xua]) # Win/DOS don't like 'aux'
+
+AX_IS_RELEASE([git-directory])
+AX_CHECK_ENABLE_DEBUG([yes])
+
+AM_INIT_AUTOMAKE([1.14 foreign no-dist-gzip tar-ustar dist-xz])
 
 # silent build if we have a new enough automake
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
@@ -37,6 +44,8 @@ AC_PROG_CC_C99
 AC_PROG_INSTALL
 AC_HEADER_STDC
 
+AX_COMPILER_FLAGS
+
 # for now, use AM_PROG_LIBTOOL, as we don't want to require
 # a too new setup for autotools/libtool
 AM_PROG_LIBTOOL