General cleanup: function headers and comments

* Use consistent style for function headers.
* Add comments to all function headers.
* Clean up some comments.
* Whitespace cleanup.
* Put include guards in all .h files.
* Remove some unused stuff.
Extracted extern variables/functions from blofeld_ui.c to midiedit.h
Fixed order of parts in Blofeld UI
Fix problem of parameters with inverted ranges scrolling the wrong way