#24 the tax burden should be adjustable

[Markus Koschany]

This is Debian bug http://bugs.debian.org/658767

"I would like to suggest an important improvement: the tax burden
should be a numeric parameter (for instance a percentage) that may be
adjusted during the game.

This way, the user could decide to decrease the tax burden in order
to stimulate the population growth (more people would be attracted
to the city, if the tax burden is lower), at the cost of getting
lower yearly tax income (until the increased population and economic
activity manages to compensate the lower tax burden).

On other side, the user could decide to increase the tax burden in
order to increase the yearly tax income, when this is needed, at the
cost of slowing down the population growth or even cause depopulation.

I think the game would become much more interesting, with this
strategic decisions to take."