Make possible to save and load processor signal chains

Source/Processors/GenericProcessor/GenericProcessor.h

.../Processors/PlaceholderProcessor/PlaceholderProcessor.cpp

...ce/Processors/PlaceholderProcessor/PlaceholderProcessor.h

...ssors/PlaceholderProcessor/PlaceholderProcessorEditor.cpp

Source/Processors/PluginManager/PluginClass.cpp

Source/Processors/PluginManager/PluginClass.h

Source/Processors/PluginManager/PluginManager.cpp

Source/Processors/PluginManager/PluginManager.h

Source/Processors/ProcessorGraph/ProcessorGraph.cpp

Source/Processors/ProcessorManager/ProcessorManager.cpp

Source/Processors/ProcessorManager/ProcessorManager.h

Source/UI/EditorViewport.cpp

Source/UI/ProcessorList.cpp