Fix bug in order to show correct balance

Before the bug fix, when the user changed the monthly
budget to another value after the daily budget was
recounted already - the balance stayed at zero - since
it only took the value of the the recounted daily budget
even though a new budget has already been set

-add a time stamp to monthly budget setting
-compare which came first - the daily budget balancing
or the new monthly budget setting and use the one that
came later