Invalid negative reference count when deleting a chatroom

[taoeffect]

Problem

1. Create a chatroom
2. Delete it

Solution

Don't know how this snuck in...

[corrideat]

It looks like this issue was introduced by moving the call to /release into the leaveChatRoom file. This is most certainly incorrect, because that function is called 'optimistically' in the side-effect, meaning that it could potentially be called multiple times. In addition, it's better architecturally for the call to /release to be made by the group contract, as it's the one 'managing' references to the chatroom contract (i.e., the one that called /retain on it).

I see there were other changes related to reference counting (such as excluding ourselves). I see those were made to fix issues, but I'll investigate further as it shouldn't be needed to check for ourselves. These types of bugs (negative counts) can indicate issues with reference counting in general or faulty reference management logic. I'll be investigating these issues.