Separate interface code

Move the QR code out from the interface code. Save to audio button, play
audio from memory rather than dumping to a file and then playing from
there.
Audio to QR Code support

Can open an audio file and save as a QR code
bleurgh
Revert "bleurgh"

This reverts commit 57ce2a15857775ee74e8167b4962d8aedc5d1933.
Icon

Custom Icon
Layout & file->exit

Tidy up the layout.  Add file->exit menu item (prompts to save any
unsaved data before exit too!)