Kernal SAVE does not support banked RAM

[SlithyMatt]

Regardless of what the RAM bank is set to prior to calling the kernal SAVE function, only data from bank 0 will be saved if the addresses specified are within the banked RAM window ($A000-$BFFF). At minimum, that should work, as it does with the LOAD function, by keeping the user selection for RAM bank while saving data to a file. Ideally, a function to save data spanning multiple banks would be available.