Updates the savegame.json file format:
* Levels now have a UUID value assigned at first save.
* The savegame.json will now track level completion/score based on UUID,
making it robust to filename changes in either levels or levelpacks.
* The savegame file is auto-migrated on startup - for any levels not
found or have no UUID, no change is made, it's backwards compatible.
* Level Properties window adds an "Advanced" tab to show/re-roll UUID.
New JavaScript API for doodad scripts:
* `Actors.CameraFollowPlayer()` tells the camera to return focus to the
player character. Useful for "cutscene" doodads that freeze the player,
call `Self.CameraFollowMe()` and do a thing before unfreezing and sending the
camera back to the player. (Or it will follow them at their next directional
input control).
* `Self.MoveBy(Point(x, y int))` to move the current actor a bit.
New option for the `doodad` command-line tool:
* `doodad resave <.level or .doodad>` will load and re-save a drawing, to
migrate it to the newest file format versions.
Small tweaks:
* On bounded levels, allow the camera to still follow the player if the player
finds themselves WELL far out of bounds (40 pixels margin). So on bounded
levels you can create "interior rooms" out-of-bounds to Warp Door into.
* New wallpaper: "Atmosphere" has a black starscape pattern that fades into a
solid blue atmosphere.
* Camera strictly follows the player the first 20 ticks, not 60 of level start
* If player is frozen, directional inputs do not take the camera focus back.
Noah Petherbridge
cf1bc81f25