Essential-Commands

98666d18 - Allow nickname to be set by command blocks...

Allow nickname to be set by command blocks... This includes some breaking permissions changes: - By default, using **Placeholders** in nicknames requires an OP level of 2 (from 4) - By default, using **entity selectors** in nicknames requires an OP level of 2 (from 4) Other changes: Add `FeedbackReceiver`, `IFeedbackReceiver`, which `PlayerData` implements, to allow easily implementing commands for us by players _or_ command blocks.