* Add RGBA color blending support in WASM build.
* Initial texture caching API for Canvas renderer engine. The WASM build
writes the chunk caches as a "data:image/png" base64 URL on the
browser's sessionStorage, for access to copy into the Canvas.
* Separated the ClickEvent from the MouseEvent (motion) in the WASM
event queue system, to allow clicking and dragging.
* Added the EscapeKey handler, which will abruptly terminate the WASM
application, same as it kills the window in the desktop build.
* Optimization fix: I discovered that if the user clicks and holds over
a single pixel when drawing a level, repeated Set() operations were
firing meaning multiple cache invalidations. Not noticeable on PC but
on WebAssembly it crippled the browser. Now if the cursor isn't moving
it doesn't do anything.
* Refactor the event system in the WASM render engine to serialize the
async JavaScript events into a channel, so that queued events are read
off serially in the main loop similar to SDL. This fixes keyboard
input issues, altho if you type really fast some input keys get lost.
* Initial WebAssembly build target for Doodle in the wasm/ folder.
* Add a new render.Engine implementation, lib/render/canvas that uses
the HTML 5 Canvas API instead of SDL2 for the WebAssembly target.
* Ported the basic DrawLine(), DrawBox() etc. functions from SDL2 to
Canvas context2d API.
* Fonts are handled with CSS embedded fonts named after the font
filename and defined in wasm/index.html
* `make wasm` builds the WASM program, and `make wasm-serve` runs a dev
Go server that hosts the WASM file for development. The server also
watches the dev tree for *.go files and rebuilds the WASM binary
automatically on change.
* This build "basically" runs the game. UI and fonts all work and mouse
movements and clicks are detected. No wallpaper support yet or texture
caching (which will crash the game as soon as you click and draw a
pixel in your map!)
