Ensure that plugin entry points are always exported on macOS and Linux (otherwise, plugins won't load in macOS release builds)

* Added possibility to auto-save/load parameters for each created
  plugin.
* Some fixes needed for LookAndFeel code generation.
* Fixed plugin type wasn't loaded correctly into PluginGenerator after
  restarting.
* Fixed boolean parameters stored incorrect values inside.
* Fixed some bugs with parameters.

* Fixed OE_GUI_MoonShard template;
* Added possibilty to create Source plugins either using
  DataThread or Processor classes in more convenient way
  (as discussed with Josh before);
* Fixed code template for FileSource plugins;
* Fixed minor bug related with TiledButtonGroupManager class;
* Now the plugin's folder is selected by default when creating new
  plugins.
* Some minor refactoring.

* Added feature to create plugins using VisualizerEditors;
* It's possible to manipulate with GUI content both of GenericEditor's
  plugin component and Visualizer canvas (in the tab or window);
* Created file templates for VisualizerEditor and Visualizer (Canvas);
* VisualizerEditor class minor improvements;
* Other minor improvements;
* Refactoring and stylystic fixes.

* 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.

* Added template for creating appropriate JUCE GUI component which will
  be automatically created inside plugin editor.
* Some improvements to the editor plugin template due to the addition
  of GUI component inside it.
* Added possibility to change desired with of the plugin in the config.
* Some minor improvements.
* Some stylystic fixes.

* Added ParametersEditor;
* Some improvements of Parameter class;
* Added possibility to generate code for parameters;
* Added possibility to save/load parameter in the project file.
* Other major and minor improvements.

* 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.