Issue #1315180 by xjm: Use select boxes instead of radios and checkboxes in grant configuration form.

Issue #1294986 by xjm: Use a string for menu access callbacks to prevent errors on certain platforms.

Issue #1243244 by xjm: Re-enable and re-select disallowed defaults on submission to prevent validation issues for required, multiple-value fields.

by xjm: Rename _taxonomy_access_format_grant_record() to _taxonomy_access_format_node_access_record() for clarity.

by xjm: Reduce memory overhead of affected nodes cache (do not cache duplicates and stop caching if there are more nodes than the max threshold).