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-dgraph/main.c

@@ -442,7 +442,7 @@ int
 main(int argc, char **argv)
 {
 	prop_dictionary_t plistd, confd = NULL;
-	struct xbps_handle xh;
+	struct xbps_handle *xhp;
 	FILE *f = NULL;
 	char *outfile = NULL;
 	const char *conf_file = NULL, *rootdir = NULL;
@@ -484,9 +484,13 @@ main(int argc, char **argv)
 		usage();
 
 	/* Initialize libxbps */
-	memset(&xh, 0, sizeof(xh));
-	xh.rootdir = rootdir;
-	xbps_init(&xh);
+	xhp = xbps_handle_alloc();
+	if (xhp == NULL)
+		die("failed to allocate resources");
+	if (rootdir)
+		xhp->rootdir = prop_string_create_cstring(rootdir);
+	if (xbps_init(xhp))
+		die("failed to initialize libxbps");
 
 	/*
 	 * Output file will be <pkgname>.dot if not specified.