* Fix crash in Audio File Processor
Fix a crash in the Audio File Processor that occurs when an Audio File Processor with a reversed sample is loaded from a save file and then the plugin window is opened.
The problem was caused by a call to `AudioFileProcessorWaveView::slideSampleByFrames` during the execution of constructor of `AudioFileProcessorWaveView`. In that situation the three `knob` members were all `nullptr` because for some reason there was an explicit setter for them which was only called after construction. This is fixed by passing and setting the knobs in the constructor.
Another question is if it's not a problem in the first place that the knobs are given to the `AudioFileProcessorWaveView` instead of their underlying models.
## Extract views
Extract the classes `AudioFileProcessorWaveView` and `AudioFileProcessorView` into their own files.
Reformat the new classes by removing unnecessary whitespace and underscores. Add spaces to if-statements.
Cleanup the includes.
## Remove friend relationship
Remove the friend relationship between `AudioFileProcessor` and `AudioFileProcessorView`.
Introduce getters for entities that the view is interested in.
