Saving only last operation

Side notes first: - it would make sense to combine `author_reward_operation` into `comment_reward_operation` - they only exist one after another and they always have the same involved comment and account; we are getting rid of one operation per comment that way - it would make sense to calculate sum of curator rewards during actual payout and put that information in `comment_reward_operation` as well; we will no longer need to handle `curation_reward_operation` when updating post information (the operation itself is still needed as it involves curator account which is different from author) Now, the changes of this commit won't work because they break operation order and it is essential. In particular you'll get different results if you have `effective_comment_vote_operation` first and `comment_reward_operation` second (pending will be zero as the latter cancels effects of the former), then when they are in opposite order. You cannot group operations by their type, they have to remain grouped by key as they were. If the side notes are applied then the simplest thing to do is to iterate original operations **in reverse**, since last operation wins (*): - when key is not present and you get `vop=comment_reward_operation` you create record `comment_payout_ops[key] = { vop, None, None, author, permlink }` - when key is not present and you get `vop=effective_comment_vote_operation` you create record `comment_payout_ops[key] = { None, vop, None, author, permlink }` - when key is not present and you get `vop=comment_payout_update_operation` you create record `comment_payout_ops[key] = { None, None, True, author, permlink }` - when key is present and you get `vop=comment_reward_operation` you supplement the record with `comment_payout_ops[key].first = vop` (* you can do this safely as long as the range of blocks is 1000 and not close to 28k+ when you could encounter more than one such operation with the same key) - when key is present and you get `vop=effective_comment_vote_operation` if both `first` and `second` are `None` (only `True` on `third`) you supplement the record with `comment_payout_ops[key].second = vop`, otherwise you ignore the operation - when key is present and you get `vop=comment_payout_update_operation` you can probably assert since that is not possible As you can see I've also proposed putting `author` and `permlink` in the above record instead of in `val` for each operation.