get Setting
Should be called inside generation process (IGenerator.generate). Method tries to obtain following setting from SettingsHolder.settings in following order:
For current rd model entity this:S and current generator settingCtx (new setting key.forGenerator(settingCtx)
For Declaration it search not specialized property (without forGenerator) in parent's SettingsHolder.settings of current rd model entity, i.e. Declaration.pointcut (e.g. Ext or Root)