IDocument: Remove unused enum.

Change-Id: I30eb3855fa4e8e59195cb865c712cdc171700af3
Reviewed-by: David Schulz <david.schulz@digia.com>

src/plugins/coreplugin/idocument.h

@@ -51,12 +51,6 @@ public:
         IgnoreAll = 2
     };
 
-    enum Utf8BomSetting {
-        AlwaysAdd = 0,
-        OnlyKeep = 1,
-        AlwaysDelete = 2
-    };
-
     enum ChangeTrigger {
         TriggerInternal,
         TriggerExternal