install plugins by default

configure.ac

@@ -2094,9 +2094,9 @@ AC_SUBST(STD_FILTERS,[$std_filters])
 
 # If user wants, then install selected standard filters
 AC_MSG_CHECKING([whether and where we should install plugins])
-AC_ARG_WITH([plugin-dir], [AS_HELP_STRING([--with-plugin-dir=<absolute directory>|no|--without-plugin-dir],
+AC_ARG_WITH([plugin-dir], [AS_HELP_STRING([--with-plugin-dir=<absolute directory>|yes|no|--without-plugin-dir],
               [Install selected standard filters in specified or default directory])],
-	      [],[with_plugin_dir=no])
+	      [],[with_plugin_dir=yes])
 AC_MSG_RESULT([$with_plugin_dir])
 if test "x$with_plugin_dir" = xno ; then # option missing|disabled
     with_plugin_dir=no