Remove FIXME which was resolved in the previous commit
Resolve TODO
Don't use WeakReference:
WeakReferences get garbage collected at EVERY gc.
Revert "Don't use WeakReference:"
WeakReference only gets GCed if there is no strong reference to the object anymore.
SoftReference only MAYBE gets GCed if there is no strong reference anymore. But we definitely want the PluginReplySend to be GCed if the connected plugin is gone

This reverts commit bc6c8dd9c37e7a541c6307736c0dda9514021f0c.