randomly_gen_new_funding() does not consider exit tribute size

[randomshinichi]

The function that randomly generates new money going into the funding pool does not take into account speculators' reactions to the size of the exit tribute.

Might want to simulate trading volume instead, and then the exit tribute off that, which will then become the generated funds, because simply randomly generating the funds based on sentiment does not take into account how speculators behaviour is affected by the exit tribute size.

It does however consider that speculators will stay away from the Commons if it is too poor. We might want to keep that.