util/wmiv: add image auto orientation detection

Based on libexif feature, this patch is adding orientation
detection and provides 2 more shortcuts for live
right/left rotation. Internal version was bumped to 0.7.

m4/wm_libexif.m4

@@ -0,0 +1,34 @@
+# wm_libexif.m4 - Macros to check proper libexif
+#
+# Copyright (c) 2014 Window Maker Team
+#
+# 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
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+# WM_CHECK_LIBEXIF
+# -------------
+#
+# Checks the needed library link flags
+# Sets variable LIBEXIF with the appropriates flags
+AC_DEFUN_ONCE([WM_CHECK_LIBEXIF],
+[AC_CHECK_HEADER([libexif/exif-data.h],
+	[AC_CHECK_FUNC(exif_data_new_from_file,
+		[LIBEXIF=],
+    		[AC_CHECK_LIB(exif, [exif_data_new_from_file],
+		[LIBEXIF=-lexif],
+		[AC_MSG_WARN(Could not find EXIF library, you may experience problems)
+		LIBEXIF=] )] )],
+	[AC_MSG_WARN([header for EXIF library not found])])
+AC_SUBST(LIBEXIF) dnl
+])