* Add new pkg/drawtool with utilities to abstract away drawing actions
into Strokes and track undo/redo History for them.
* The freehand Pencil tool in EditorMode has been refactored to create a
Stroke of Shape=Freehand and queue up its world pixels there instead
of directly modifying the level chunker in real time. When the mouse
button is released, the freehand Stroke is committed to the level
chunker and added to the UndoHistory.
* UndoHistory is (temporarily) stored with the level.Level so it can
survive trips to PlayScene and back, but is not stored as JSON on
disk.
* Ctrl-Z and Ctrl-Y in EditorMode for undo and redo, respectively.
* 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)
* Add some encoding/decoding functions for binary msgpack format for
levels and doodads. Currently it writes msgpack files that can be
decoded and printed by Python (mp2json.py) but it can't re-read from
the binary format. For now, levels will continue to write in JSON
format.
* Add filesystem abstraction functions to the balance/ package to search
multiple paths to find Levels and Doodads, to make way for
system-level doodads.
