Economy: Display what is affecting the players science, gold, and other stats

[RyanGrieb]

We need to modify StatLine, where when we addValue, subValue, or mergeValue. This would include a description of what is modifying it. For instance, in the MarketBuilding class, we would put this.statLine.addValue(Stat.GOLD_GAIN, 2, "Market"); And store that information to be referenced by the client later.