Implement equals for `EntryTableValue`?

[ThibaudDauce]

I had a bug during my tests when comparing two entry table values (inside the callback) with a simple ==. I don't know if Java persons don't fall into this trap but I was expecting to be able to compare two EntryTableValue to check if the previous one was the same as the value stored inside my in memory database. Don't know if it's something really useful (users will not implement in memory database).