FS#6397 - Keep town growth rate in sync with house count
I had this thing on my mind for quite a while, but separation of growth rate from growth flag I did for #6378 makes it a lot easier.
Right now town growth rate is normally updated only once a month. This have a nasty side-effect of town growth speed being influenced by game date. It's especially troublesome in citybuilder. For example, imagine two cities that are very close on growth, just one is a day behind the other. At some point they switch from growing 1 house in 2 days to 1 house every day. But first city does it on 31 dec and second would've done it on 1 jan but because of monthly update it only gets it on 1 feb. So, suddenly, on 1 feb first city is 15 houses larger than second one only because it was lucky to get its growth changed before the new month.
So instead of monthly updates this patch keeps town growth rate in sync with house count. It is supposed to be applied on top of my patch for #6378.
This task depends upon