Dialog pieces only some players see, upright progress bars, and an update notice

• A piece of a Studio dialog can be shown only to some players: by a setting they chose in the dialog, a value, or a permission.
• Progress bars in Studio dialogs can stand upright, filling from the bottom, and fade between two colours.
• When a newer RP Engine is on SpigotMC, the console says so on startup and ops are told when they join. update-check: false turns it off.
• The anonymous usage count now includes how many players are online, as a single number. telemetry.enabled: false still turns it off.
• Fixed: when a dialog's list got shorter (a player's history after a punishment was removed, say), the rows past the end were hidden but their words were still drawn.