Removes the knob image knob04.png. This knob corresponded to
knobGreen_17 which was not used anywhere in the code. To be able to
remove the enum value it was necessary to change the knob loading code
in Knob::onKnobNumUpdated. However, the changed implementation is more
explicit and therefore likely better to understand.
The piano roll's actions have been grouped into several toolbars. There
are now five groups / tool bars: "Transport controls", "Note controls",
"Copy paste controls", "Timeline controls" and "Zoom and note controls"
(this group is a bit mixed). Each group can be turned off and on using
the standard toolbar context menu provided by Qt.
The new default layout of the toolbars saves horizontal space by putting
the "Zoom and note controls" below the other toolbars. The toolbars can
be hidden and shown via the context menu but these states are not
stored.
The "Song editor", "Beat+Bassline editor" and "Automation editor" have
been switched to using movable toolbars as well.
Adjusted the Editor class to have some other defaults for the "Transport
controls".
Added some methods to add toolbars to editors and changed the other
editors' code to use it. This way the properties of a standard editor
toolbar can be changed in a simple and central way.
Fixed the size of the timeline control buttons which are implemented as
NStateButton. Previously these had a fixed size and appeared smaller than
all other buttons. Now they behave like other ToolButton with respect to
the size. Also removed a fixed size call in ToolButton itself.
Made some adjustments to the CSS for QToolBar and QToolButton:
* Switched the QToolBar CSS to a vertical gradient and also increased
the padding to 2px on the way.
* Previously all buttons looked like they were pressed. This was fixed by
using the same linear gradient that is used for the QToolBar.
* The hover effect for QToolButtons is a bit more subtle now and looks
less intensive as when the button is pressed / checked.
* Gave the normal buttons a bit more radius.
* Adjusted the radii of the special play and stop buttons to be
symmetric so the do not look skewed.
