* Rework PianoRoll paintEvent + some extras
* Split out PositionLine class to own file
* Refactor PianoRoll Q_PROPERTYs
* Reduce code by using Q_PROPERTY's MEMBER function and removing getter/setter functions
After looking at the getters and setters, they did nothing different than what direct
access would allow. Nothing outside of PianoRoll used the public functions as well.
Considering these factors we can reduce the number of functions by 2x the number of
Q_PROPERTIES, and go with direct access instead.
* Remove need for keyboard pixmaps
With the recent change to allow zooming vertically, aligning pixmaps is a PITA. Since
we have themes which can take brushes and colors, it would be simpler to take a solid
color or a gradient with some extra style properties to resize the keys and text colors.
While it will slightly be a downgrade from pixmaps since they can be anything really,
this will allow us to customize the piano roll further moving forward.
* Added the ability to update margins for TimeLineWidget and StepRecorderWidget
These take a X coordinate, which was hardcoded to WHITE_KEY_WIDTH, and never looked
back. Now we can adjust on the fly if we need to. Currently this just allows us to
shift the left margin to the style-defined white key width.
* Fix phantom pixmaps when PianoRoll not focused
* Update PositionLine class changes related to #5543
(Addresses #1421)
**Behaviour description:**
* Toggle step-recording mode using the dedicated icon.
* This mode is mutually exclusive with other recoding modes (record/record
accompany).
* Step-Recording while song is playing is allowed (and fun! :) ).
* When start recording, the start recording-position will be set where the
timeline curser points (quantized backwards using PianoRoll's current
quantization). If step-recording is started while the pattern is playing the
start recording-position is set to the beginning of the pattern.
* Step length is determined by the Piano Roll's current note-length (can be
changed dynamically during step-recording).
* The record-position can be moved forward/backward using the right/left keys.
* When notes are pressed on keyboard/midi-device, they will be added
temporarily ("recorded") with a length of a step. while still pressed, user
can adjust the length by steps resolution using the arrow keys (e.g. moving
right once will make the note's length 2-steps, another right press will make
the length 3-steps etc.).
* When all pressed-keys are released, the actual recording happen and the
notes are added.
* If the user press multiple notes, and release some of them for some time
which indicates it is intentional i.e. he didn't want to do a full release
to record the step but rather just change what will be recorded (I set the
"intentional release threshold" to 70 milliseconds) - these note will be
removed from current step-recording. e.g.
* Added notes are not quantized, making the addition simpler and WYSIWYG
* Similiarly to adding notes using mouse clicks, an undo-checkpoint is added
per added step and not for the whole recording as in other record modes.
