Adding inheritance to permissions

Issue Summary

The attached patch allows permissions to be set to Y (yes/allow) N (no/deny) or - (keep as is). To access these additional features you need to click on the 'advanced settings' box in the nodeperm_role setting page. The box, which is off by default, retains the current usage. If the advanced settings is cheeked then editing the applicable nodeperm_role action will show the new interface populated with any existing data.

I use this in actions to add or remove a permission without changing any others.

Also included is a patch to make sure the node access table properly deletes entries and the patch to allow edit/view to be different.