Assets

Pending bug: need to write writePlayer so that player.totalIncome
displays correctly.  Right now filefetch.getPlayer only returns a new
player, which does not match up when retrieving assets (because
asset.income checks to make sure that player is the same player).
Assets

Fixed minor bug regarding use of assets.add; imperial bonds was being
ignored because it was declared as a generic asset instead of
infrastructure as it should be.