* 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.

* All modules are replaced with the JUCE 4.2.1 ones;
* Introjucer was replaced by Projucer;
* Also some appropriate needed fixes for Makefile.plugins;
* Removed -fvisibility=hidden flag for Linux building.