* Updated images for collapse/show button;
* Updated animations;
* Some other small UI improvements;
* Added possibility to collapse element by clicking "ESC" key
  either on the component itself or on the TextEditor.

* Created SlicerChannelSelectorComponent class which holds inside
  all ChannelSelector's parser related components and which
  takes responsibility for parsing selected range, etc.
* Added possibility to collapse parser related components.
* Added animations.
* UI improvements.
* Minor bugs fixes.

* Implemented sliders' material lookAndFeel;
* Material lookAndFeel have been applied to sliders;
* Improved UI layout for panel.
* Adjusted positioning of elements during resizing.
* New icon for "Mute" button;

The control panel now holds an "AudioEditor" to adjust volume
and open a window to alter device settings. Audio output is definitely
working, but different buffer sizes make it sound really weird. The
same problem is present in the Juce demo app, however, so I don't
think it's a problem inherent in the GUI.