Add option to use quarter notes per minute instead of beats per minute (=fixed time signatures)

Could time signatures be fixed. When set to compound meters, like 7/8 the speed of the click should change to eighth notes instead of staying quaters like it currently does.

Changed the title from "Time signatures" to "App: add option to use quarter notes per minute instead of beats per minute (=fixed time signatures)"

Hey Daniel, if I understand you correctly you'd like to use fixed quarter notes per minutes as a standard, instead of beats per minutes, so when you change the time signature to something other than quarter notes the speed should speed up or slow down. Noted on your suggestion!