Improve how "available_trades.pl" shows plans

Fixes how plan quantity is handled, showing actual quantity instead of always 1. Also allows display of the plan level. Also fixes comma-separated quantities.

before this change, examples/available_trades.pl would always shows plans as being qty 1 and not show the levels. Also, if qty was very high, it would contain a comma coming back from the server, which broke the qty display.

ps. I seem to have made a mistake with GIT, I only intended to submit 8b58139. I believe that I submitted 8290777 separately a while ago.