True if the plug-in is cleaned successfully, false otherwise.

This method is intended to be called after the completion of execution of a plug-in to fully clean any data that was necessary during execution. All data structure and file lists should be cleaned. Optionally, custom properties of a plug-in may also be cleaned, though this method will allow plug-in developers the opportunity to not clean custom properties and only destroy what needs to be destroyed. It should be assumed that if the clean fails, the plug-in will be destroyed and recreated, negating all saved states. It is extremely important for plug-in developers to release all memory they no longer require following plug-in execution by way of this method.