Remove more unused things from CryCommon and CrySystem. (#709)

Lots of unrelated removals, I basically tried to remove everything exposed via gEnv that isn't used anymore, and following the threads found a few other things to remove also.

Code/Sandbox/Editor/CryEdit.cpp

@@ -85,7 +85,6 @@ AZ_POP_DISABLE_WARNING
 // Editor
 #include "Settings.h"
 
-#include "Include/IBackgroundScheduleManager.h"
 #include "GameExporter.h"
 #include "GameResourcesExporter.h"
 
@@ -2314,15 +2313,6 @@ int CCryEditApp::IdleProcessing(bool bBackgroundUpdate)
     #endif
     }
 
-    // process the work schedule - regardless if the app is active or not
-    GetIEditor()->GetBackgroundScheduleManager()->Update();
-
-    // if there are active schedules keep updating the application
-    if (GetIEditor()->GetBackgroundScheduleManager()->GetNumSchedules() > 0)
-    {
-        bActive = true;
-    }
-
     m_bPrevActive = bActive;
 
     AZStd::chrono::system_clock::time_point now = AZStd::chrono::system_clock::now();