Update Spell message (BagOfHolding)

[ago1024]

• The examine message for BagOfHolding says it's a Courier. This can probably be fixed by using a custom EXAMINE ActionPerformer
• There are "new" on screen messages for spells. Add this for the courier spell too

[Tokeiito]

Could you please add better descriptions for issues, so that someone from side could help with them :)