Cleaned up 20IntHaskellExercises.hs

Just fixed the indentation on the banana definition in the misty
instance for State
Cleaned up code for number 443

Sure, it still won’t go in reasonable time, but at least now it could
*in theory* work.  I’d just need to leave it running for far longer
than I want to.
Added matrix multiplication to Arithmetic.hs

Yup!
Added my own implementation of transpose

Just thought it’d be fun to write