Increase merchant starting funds

[kyres1]

This is a pretty simple fix to make the merchant role considerably more fun. As it stands there is basically no way to obtain enough money to pay back the 4,000 credits merchants start with without rolling traitor. I don't see why it's so low when 90% of the items available are larger than your entire starting funds. Raising it to 10-20,000 would make for much more variety with what merchants can buy and contribute to the round.