MacroManager#exists is not consistent with the behaviour of MacroManager#getMacro

MacroManager#getMacro always try to fallback on searching for the macro name without the syntax, while exists only check the given macro id, with the syntax exists.
IMO if MacroManager#exists returns false then MacroManager#getMacro with same id shouldn't return anything.

I propose to fix that by providing a new MacroManager#exists method with a boolean flag to avoid any breakage.