Get rid of more static memory

* Replace backend_is_init (formerly is_init) with relationships_table

* Remove deprecated functions that used static variables

* Move static "bound" variable to MdbHandle as relationships_values

include/mdbtools.h

@@ -272,7 +272,8 @@ typedef struct {
 	GPtrArray	*catalog;
 	MdbBackend	*default_backend;
 	char		*backend_name;
-    int          backend_is_init;
+	struct S_MdbTableDef *relationships_table;
+	char        *relationships_values[5];
 	MdbFormatConstants *fmt;
 	MdbStatistics *stats;
     char date_fmt[64];