Priority variable is taken even when defaults are not set

There is a bug in this module with the access priority with respect to nodetype default access.

When the default values nodetype are not set, the module should have no effect on the access rights of that nodetype. But there is a variable set with name nodeaccess_nodetype that gets set with empty values.

If the priority variable is checked, then when the node_access_acquire_grants function is called, it just deletes all the other node_access records for a node of that nodetype.

Ideally the module should leave this node alone as there were no nodeaccess set for the node or the nodetype.

This way the nodeaccess module will run over other accesses only when it is explicitly asked to for a nodetype or for a node and not just blindly overwrite other accesses set by modules such as organic groups.