Bank Offset should accept values greater than 128

[mqnc]

The text input for the bank offset in the soundfonts setup is limited to 128. Fluidsynth allows for much higher offsets and the 128 is very limiting if you want to load several soundfonts and address them all via midi.

[rncbc]

Fixed on git head master (https://github.com/rncbc/qsynth/commit/3cec8c4)

thanks