Update shop.py
Update shop.py

- Added Trading! can now trade items with other players registered to the shop. Players can also choose to block trades, and there is a settable cooldown.
- Added ability to change the output to whisper mode or chat mode for inventory and shop list commands.
- All shop configuration commands under !setshop group command.
- Changed points to credits to align with Economy nomenclature
- Fixed some minor bugs
-  Several under the hood changes to the code organization
OldManMarsh/Jumper-Cogs