Closes #1272

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

Code preparation for scalable LEDs, Dials and Buttons

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@falktx.com>

Signed-off-by: falkTX <falktx@gmail.com>

* patchcanvas: Working Ctrl for rubberband selection

* patchcanvas: optimize calls in zoom-fit

* patchcanvas: optimize fixScaleFactors

* patchcanvas: speedup zoom_in/zoom_out

* patchcanvas: disconnect ports by Ctrl+MidButton

* patchcanvas: optimize rubberband update

* patchcanvas: correct cursor unset

* fixScaleFactor: support transform argument

* patchcanvas: speedup wheelEvent handler

Direct operations on QTransform go faster than via QGraphicsView
convenience methods.

* patchcanvas: optimize QPointF construction

* patchcanvas: Сursor for connection cut mode

* patchcanvas: rubberband scaling support

* patchcanvas: Limit top scale by canvas size

* patchcanvas: Fix box position after each movement, even creation

* minimap: Scaling support

Pressing RMB after LMB activates special scaling mode. Scroll wheel to
scale in any mode or without such.

* patchcanvas: Take port lineHinting from chosen pen

* patchcanvas: Set default port offset to 0px

Besides of more tidy look with certain themes, it also noticed to be
workaround for problem, when connection lines get under port's parent
box, after selection changes.

* patchcanvas: Finer connection placement relative to ports

Closes #343