## Scalable LFO graph
Make the rendering of the LFO graph scalable. Change the fixed size to a minimum size. Adjust the rendering code such that it uses the width and height of the widget instead of the background pixmap.
Only draw only poly line once instead of many line segments. Collect the points in the for-loop to be able to do so. This makes the code a bit more understandable because we now compute exacly one point per iteration in the for-loop.
Use the same interpolation for the line color like in the envelope graph.
Rename some variables to make them consistent with the other code.
Remove the member `m_params` which is not used anyway. This also allows for the removal of the overridden `modelChanged` method.
## Use "Hz" instead of "ms/LFO"
Use the more common unit "Hz" to display the frequency of the LFO instead of "ms/LFO". The frequency is always displayed with three digits after the decimal separator to prevent "jumps".
## Take "Freq * 100" into account
This commit fixes a bug where the "Freq * 100" option was not taken into account when computing and displaying the frequency of the LFO.
## Keep info text legible
Draw a slightly transparent black rectangle underneath the text to keep it legible, e.g. for high frequencies with an LFO amount of 1 which results in a very bright and dense graph.
## Extract drawing of info text into method
Extract the drawing of the info text into its own private method `drawInfoText`.
Move the envelope and LFO graphs into their own classes.
Besides the improved code organization this step had to be done to be able to use layouts in `EnvelopeAndLfoView`. The class previously had fixed layouts mixed with custom rendering in the paint event. Mouse events are now also handled in both new classes instead of in `EnvelopeAndLfoView`.
## Layouts in EnvelopeAndLfoView
Use layouts to align the elements of the `EnvelopeAndLfoView`. This removes lots of hard-coded values. Add helper lambdas for the repeated creation of `Knob` and `PixmapButton` instances.
The spacing that is explicitly introduced between the envelope and LFO should be removed once there is a more open layout.
## Layouts for InstrumentSoundShapingView
Use layouts to align the elements of the `InstrumentSoundShapingView`.
## Info text improvements in LFO graph
Draw the info text at around 20% of the LFO graph's height. This prepares the dialog to be scaled later.
Write "1000 ms/LFO" instead of "ms/LFO: 1000" with a larger gap.
## Accessors for EnvelopeAndLfoParameters
Make the enum `LfoShape` in `EnvelopeAndLfoParameters` public so that it can be used without friend declarations. Add accessor methods for the model of the LFO.
## Other improvements
* Adjust include orders
* Variable initialization in headers
* Prevention of most vexing parses
