syncing changes from ssc svn, mostly.

[Course.cpp] HasTimedMods() now actually checks for timed mods (technically non-global) instead of being a clone of HasMods()
[Player.cpp] add MAX_HOLD_LIFE/[Player] MaxHoldLife metric
[ScreenGameplay] looking into places to put loading of replay data, perhaps?
[elsewhere] lots of cleanup, and I'm sure there's lots more to be done.
add a todo to ProductivityHelpers.

src/ScreenGameplay.cpp

@@ -2811,6 +2811,12 @@ void ScreenGameplay::SaveReplay()
 	}
 }
 
+/*
+bool ScreenGameplay::LoadReplay()
+{
+	// Load 
+}
+*/
 
 // lua start
 #include "LuaBinding.h"