Fix old placeholders not removing from registry

[NicoNekoDev]

Pattern.equals() compares the references to the objects, i.e. uses the == operator. This is not good, because a new Pattern is created for the new placeholder, so the above mentioned method throws false even tho it's the same pattern.
https://stackoverflow.com/a/10055112
This fixes the issue with reloading libreforge's custom conditional placeholders that did not work correctly.