Suggestion: Reducing upgrade costs.

```
Upgrades are awesome, because they save a lot of space, but the output per
credit is much lower. Right now the output from upgrades is twice as expensive
for some buildings (power plants) and four times more expensive for others
(houses, food etc.).
This is not so much a problem for the rich player (who normally also needs the
space), but the AI really throws away a lot of money on those upgrades.

My suggestion would be to reduce the penalty for plants, hospitals, police,
food factories and power plants to 25%. (100% more output for 125% the credits)
The other buildings are fine as they are. They are supposed to be limited
anyways :)

A little side note on upgrades: It would be really nice if the buildings kept
producing while they are being upgraded. (I've sometimes even had colonies
surrender to me and to my enemies, because they upgraded power plants at a bad
moment and lost happiness)
```

Original issue reported on code.google.com by `silvernt...@msn.com` on 30 Jun 2012 at 6:46