Inventories, built-in placeholders, and no more clashes with emoji plugins

Drawn dialogs

• The player's inventory now fills in: items in live slots are drawn with their icons, counts and tooltips, and players can pick items up and move them between slots, exactly as on RP Engine.
• Built-in placeholders work in drawn dialogs: {level}, {xp}, {xp_points}, {xp_needed}, {health}, {health_max}, {food}, {ping}, {world}, {x} {y} {z}, {gamemode}, {online}, {time} and more, so a level bar fills without PlaceholderAPI.
• Dialogs drawn from today keep their pictures in a font of their own, so plugins that put emojis or HUD images in the default font (CraftEngine, ItemsAdder, Nexo, Oraxen, BetterHud and others) can no longer replace them, and a dialog can no longer break their HUD. Dialogs you already have are redrawn this way automatically on the first start (this needs the internet once), and unedited samples are updated in place.
• Two drawn dialogs with the same name from different packs no longer overwrite each other's pictures.

Studio

• The dialog editor can now download a dialog straight for Dialog Engine: unzip it into plugins/ and run /de reload.