Revert "Revert "Normalize potmeter widget values to [0.0, 1.0] instead of [0.0, 127.0].""

This reverts commit 6fcd283cd80a34747320340ecc9a17b9b4b9606a.
Minor refactoring in Midi to Control path
Merge pull request #2 from daschuer/potmeter_fix

Minor refactoring in Midi to Control path
Fix WKnob / WDisplay active pixmap calculation to bias towards the lower of the two middle pixmaps when there are an even number.
Rename widget parameter to parameter.
Revert some, but not all hotcue seeks to seekAbs instead of seekExact.

In general, seeks for goto-and-stop should be exact, or else users will
wonder why the playhead is not exactly on the hotcue. But
when actually playing the track, hotcues should obey phase alignment.
Merge pull request #143 from rryan/potmeter_fix

Normalize potmeter widget values to [0.0, 1.0] instead of [0.0, 127.0].