New configuration scheme changes, round 1.

- Configuration file 'xbps-conf.plist' has been splitted off into
  two files: conf.plist and repositories.plist. By default they
  are stored in etc/xbps.
- Changed some members in xbps_handle struct, mostly to make it easy
  to change its value in {cache,root}dir and conffile.
- Made xbps_init() release proplib objects as soon as we don't need
  them, that way it uses 35% less of memory or in some cases even more.

There will be another commit that will implement to read new virtualpkg
settings by the user, as specified in:

	http://code.google.com/p/xbps/issues/detail?id=12

bin/xbps-bin/main.c

@@ -285,10 +285,15 @@ main(int argc, char **argv)
 		xhp->xbps_unpack_cb = unpack_progress_cb_verbose;
 	else
 		xhp->xbps_unpack_cb = unpack_progress_cb;
-	xhp->rootdir = rootdir;
-	xhp->cachedir = cachedir;
+
+	if (rootdir)
+		xhp->rootdir = prop_string_create_cstring(rootdir);
+	if (cachedir)
+		xhp->cachedir = prop_string_create_cstring(cachedir);
+	if (conffile)
+		xhp->conffile = prop_string_create_cstring(conffile);
+
 	xhp->flags = flags;
-	xhp->conffile = conffile;
 	xhp->install_reason_manual = install_manual;
 	xhp->install_reason_auto = install_auto;