Add the query to the `update` command to filter karas to update

Add a query to the update function used to filter the karas to update. Only the karas that matches the query will be updated.

Also refactor the URI thing, now the implementations is hidden from the rest of the code.

Partially solves #102 (closed)

inc/lektor/uri.h

@@ -61,7 +61,7 @@ void lkt_uri_free(struct lkt_uri *ret);
 
 LKT_URI_TYPE lkt_uri_get_type(const struct lkt_uri *);
 const char *lkt_uri_get_value_as_str(const struct lkt_uri *);
-size_t lkt_uri_get_value_as_int(const struct lkt_uri *);
+int lkt_uri_get_value_as_int(const struct lkt_uri *);
 LKT_URI_VALUE_TYPE lkt_uri_get_value_type(const struct lkt_uri *);
 const char *lkt_uri_get_column_name(const struct lkt_uri *);