Shop cleanup and small fixes.

- Made the shop description/content and hint text be set only when needed.
- Removed most of the dead code.
- Moved the buy/sell/trade counter to a better place and added text in front of it.
- Made the total after buy/sell/trade appear when trying to buy/sell/trade.
- Made the buy count be set to one when entering the info mode so that it's possible
to quick buy one item.

The shop mode should be much more simple to use now, and ready for finishing
the development fo trades. :)