* Created 3rd slider-page on creating project steps which is used
  to select appropriate plugin, processor type, plugin GUI template,
  other options.
* Created plugin GUI templates system;
* Created some plugin GUI templates for GenericEditor;
* ButtonGroupManager and TiledButtonGroupManager classes minor
  improvements and fixes;
* Changed index of ProcessorType::UtilityProcessor;
* Other minor bugs fixes.

* Now ChannelSelector class contains three instances
  of TiledButtonGroupManager class (AUDIO, RECORD, PARAM).
  This managers own appropriate buttons, position it, responsible
  for all animations, fuzzy selection via dragging mouse, etc.
* Button group managers minor fixes.

* This class position buttons inside itself
  as tiles and has feature which gives
  us fuzzy button selection possibility via
  mouse drag (or SHIFT+mouse drag for deselection).

* LinearButtonGroupManager class now have the same functionality as
  ButtonGroupManager class had before.
* ButtonGroupManager now is the base class for all other button group
  managers.
* Appropriate fixes in the CAR plugin.

* Fixed bug gain slider have some buggy per-channel functionality
  so it were possibility to set different gain values for only some
  channels.
* Now gain slider affects all the channels.
* Explicitly added gain slider to the CAREditor component.

* Implemented ButtonGroupManager.
  It is responsible for positioning of buttons, any animations
  during switching, etc.
* Added MaterialButtonLookAndFeel class which implements
  flat button look and feel following Google Material Design Guidelines.