* Toolbar has icon buttons for the Pencil Tool, Line Tool, Rect Tool,
Actor Tool and Link Tool.
* Remove the tab buttons from the top of the Palette window. The palette
tab is now toggled between Swatches and Doodads by the tool selected
on the tool bar, instead of the tab buttons setting the tool.
* Remove the "Link Doodads" button from the Doodad Palette. The Link
Tool has its own dedicated toolbar button with the others.
* Use `go-bindata` to embed built-in doodads and levels directly into
the Doodle binary. `make bindata` produces the bindata source file.
* Add `FromJSON()` method to Levels and Doodads to load objects from
JSON strings in memory (for bindata built-ins or WASM ajax requests)
* Update file loading functions to check the embedded bindata files.
* pkg/config.go#EditFile:
* Supports editing a level from bindata (TODO: remove this support)
* If the "assets/levels/%(simple-name.level)" exists in bindata,
edits that drawing.
* No such support for editing built-in doodads.
* WASM has no filesystem access to edit files except built-in
levels (yet)
* pkg/doodads#ListDoodads:
* Prepends built-in doodads from bindata to the returned list.
* WASM: no filesystem access so gets only the built-ins.
* pkg/doodads#LoadFile:
* Checks built-in bindata store first for doodad files.
* WASM: tries an HTTP request if not found in bindata but can go no
further if not found (no filesystem access)
* pkg/filesystem#FindFile:
* This function finds a level/doodad by checking all the places.
* If the level or doodad exists in bindata built-in, always returns
its system path like "assets/doodads/test.doodad"
* WASM: always returns the built-in candidate path even if not found
in bindata so that ajax GET can be attempted.
* pkg/level#ListSystemLevels:
* New function that lists the system level files, similar to the
equivalent doodads function.
* Prepends the bindata built-in level files.
* WASM: only returns the built-ins (no filesystem support)
* Desktop: also lists and returns the assets/levels/ directory.
* pkg/level#LoadFile:
* Like the doodads.LoadFile, tries from built-in bindata first, then
ajax request (WASM) before accessing the filesystem (desktop)
* Menu Scene: TODO, list the built-in levels in the Load Level menu.
This feature will soon go away when WASM gets its own storage for user
levels (localStorage instead of filesystem)
* On the Doodads tab is the Link button to enter the Link Tool.
* Click Link, then click the 1st doodad on the level, then click the 2nd
doodad to complete the link.
* The actors struct in the Level holds the link IDs for each actor.
