Items in "Severity" and "Priority" are not "well ordered" after deletion/addition

[Jack9]

Items in "Severity" and "Priority". Order management of items are not well ordered in cases of deletion/addition. When you delete an item that is ordered [ 1 ], you lose the ability to reorder anything to [ 1 ]. The top ordinal is effectively [ 2 ]. When adding a new item, the new item will become, [(highestorder+1)] rather than filling the order [ 1 ] slot.

Functionality should be:

When a delete occurs, reassign ordinals as per the current order from 1. Display page.

When an addition occurs, addition is assigned (highestorder+1), then reassign ordinals as per the current order from 1. Display to page.

[Matthew Good]

Duplicate of #2876.