add: foreign key support in database

add: more tests
fix: bad tag handling when finding 0 in column

main.c

@@ -84,6 +84,8 @@ main(int argc, const char** argv)
         terminate(1);
     }
 
+    sqlite3_exec(global_database, "PRAGMA foreign_keys = ON", 0, 0, 0);
+
 
     /******************** INIT ROUTER ********************/