Update task list (-1/+2).
Add `monopoly_rentfactor` rule.
Implement doubled rent in the case of a monopoly.
Fix rent calculation.

Rent doubling only happens if the property is UNIMPROVED.
Fix flow.
Add function to get last roll.

Also export the value as part of the model.
Fix logic.
Do not self-create games.
Add game name to exported model.

Deprecate getLastRoll.
Better variable names.
Let `last_roll` have a default.
Remove `whoseturn` from game table (obsolete column).
Fix SQL syntax error.
Fix array key name.
Start coding client-side view.
Rename some columns for model export.
Workaround PDO/PHP type=string dumbness.
Break out player info box to a jQuery-ui plugin.
Add [very rough] layout plan.