Added support for doubles and modal message boxes

Signed-off-by: Joel Nider <joel@nider.org>
Calculate rent for railroads & utilities

When multiple railroads or utilities are owned, the rent calculation
is a bit different than normal, since it is based on the number of
properties rather than the value of the individual property.

Signed-off-by: Joel Nider <joel@nider.org>
Added status area

Signed-off-by: Joel Nider <joel@nider.org>