[Pharo-project] some mess in 10161

BooleanScriptEditor has an obsolete superClass and should be removed. This removes some next obsolete classes: (Preferences preferenceAt: #allowEtoyUserCustomEvents) changeInformee: nil changeSelector: nil. There's one new 'undeclared' after Smalltalk cleanOutUndeclared. CPlatform used directly by HostSystemMenus class>>initialize -- Pavel