Bank Balance Earns Interest v 1.1

adds interest computations so that at the start of each month, interest is earned on a farm's bank balance. The interest is reflected in the “miscellaneous” sum on the financial screen. The default rate is 1% APY.
Two dev console commands have been introduced to modify the interest rate:
`biSetInterestRate ‘ – permits the changing of the interest rate. ex: `biSetInterestRate 0.01` would set the interest rate to the default.
`biGetInterestRate` – outputs the current interest rate to the console.



Changelog: +



V1.1 fix: @XelaNull in #1 removes global variable leaks in onPeriodChanged().



Credits:
Evan Kirsch