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.
Merge pull request #143 from rryan/potmeter_fix

Normalize potmeter widget values to [0.0, 1.0] instead of [0.0, 127.0].
Add toDebugString function for getting the equivalent of what qDebug() would
print for a class.
Make WNumber::setValue virtual and make child overrides slots.
Get rid of WWidget::getPath/setSkinPath in favor of using SkinContext for skin path resolution.
Also remove WWidget::m_qPath.
Wrap pattern of comparing strings against "false" or "true" with SkinContext::selectBool.
Make WWidget::m_bOff private.
Oops. Make selectBool callers provide default values.
Rename WWidget::setValue to WWidget::slotConnectedValueChanged.
Remove direct access to WWidget::m_value from child classes.
Remove ControlObjectThreadWidget use in WNumberPos.
Oops, I screwed up multi-state toggle buttons while getting rid of m_value access.
Fix SkinContext copy constructor to copy the base skin path.
Fix one more spot that I missed a [0,127] -> [0, 1] conversion in WWaveformViewer.
Make WLabel inherit QLabel instead of WWidget.

WLabel and its variants don't really need anything provided by WWidget. As far
as I can tell no existing CSS styles use WWidget to style WLabel either, so this
should be safe skin-wise. This also gets rid of WWidget::getComposedWidget since
its sole purpose was for styling labels.