layout autocomplete attributes and values not always correct

[dskinner]

While what's currently displayed is consistent, it's not always correct.

Some cases require attributes that are derived from it's parent, such as a RelativeLayout child autocompleting an attribute for layout_centerInParent.

Other cases involve attributes that seemingly should have autocomplete values not show up at all. Need to document some of those attributes here and dig in to sdk data values to see what the issue is.