Started working toward displaying the trade conditions.
Finished the work on showing the trade conditions.

Also fixed a crash due to mishandling the embedded image when
there were several trade conditions.
Fixed also the layout of conditions.

Trading should now be more or less complete :)

Thanks a lot to codergreen for the core work on it.
Fixed the characters placement in the shop equipment list view
Use c-formatted strings for hints in the shop mode, and translated the keys names.

The shop trade mode should now be ready for in-game use :)