Removed old / unnecessary code

* Removed Plugins.h file as I assume setting up a plugin hell is a bad
idea (does anyone disagree?).
* Removed FnIdGenerator, and moved FnIdGenerator::GenerateFnId to
getFunctionId in Modules.cpp
* Disabled RSX Debugger and Memory Viewer when the emulator is stopped.
* ELF64Loader::LoadPhdrData refactored.

rpcs3/Emu/System.cpp

@@ -407,7 +407,6 @@ void Emulator::Stop()
 	GetAudioManager().Close();
 	GetEventManager().Clear();
 	GetCPU().Close();
-	//SysCallsManager.Close();
 	GetIdManager().Clear();
 	GetPadManager().Close();
 	GetKeyboardManager().Close();