Feature: a demographics chart

[telex4]

Whilst trying to raise my production total in a game yesterday, I thought: wouldn't it be cool if freeciv provided charts in the demographics dialogue that showed the statistics over time, so you could see how things rise and fall? Often I try to refine a particular skill, like getting very productive quickly, and it's difficult to remember how well I'm doing. So it would be a useful feature as well as just being something cool to look at while you wait for your go

Also, how about letting each player see his/her allies' demographics?