Improved asset import parameters

[flatpickles]

Two problems with current approach (function-based imports):

• No defaults
• Can't reference them directly/declaratively.

A better design will solve both these problems. Maybe a helper class that can be instantiated in the parameter declaration?

assetImport = new ImageImport("/assets/default.png");

update() {
    ctx?.drawImage(assetImport.image, 0, 0);
}

TBD - more thought needed.