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

lib/package_register.c

@@ -51,7 +51,8 @@ xbps_register_pkg(prop_dictionary_t pkgrd)
 	bool autoinst = false;
 
 	xhp = xbps_handle_get();
-	plist = xbps_xasprintf("%s/%s/%s", xhp->rootdir,
+	plist = xbps_xasprintf("%s/%s/%s",
+	    prop_string_cstring_nocopy(xhp->rootdir),
 	    XBPS_META_PATH, XBPS_REGPKGDB);
 	if (plist == NULL)
 		return ENOMEM;
@@ -162,7 +163,8 @@ xbps_unregister_pkg(const char *pkgname)
 	assert(pkgname != NULL);
 
 	xhp = xbps_handle_get();
-	plist = xbps_xasprintf("%s/%s/%s", xhp->rootdir,
+	plist = xbps_xasprintf("%s/%s/%s",
+	    prop_string_cstring_nocopy(xhp->rootdir),
 	    XBPS_META_PATH, XBPS_REGPKGDB);
 	if (plist == NULL)
 		return ENOMEM;