Add AMD support

[koutoftimer]

It is more requirement rather than a feature request.

Lets take a look at pixi-plugin-example. As you can see, at this lines plugin have to be attached to global PIXI variable as well as to be exported as a standalone module with its dependencies. At some point, this repo\plugin brokes one of the main approaches of how pixi.js is functioning.

Currently, there are a lot of module loaders that are built on top of AMD. I'm one of that users. Solution for me could be:

• Remove module loading (definition, dependency management, etc.) from the whole project - totally not what I'll do.
• Replace pixi-sound with some other sound library that is not part of pixi-* package.
• Add AMD support to this plugin ASAP.

[koutoftimer]

Sorry, my fault, bad requirejs config.

[koutoftimer]

In order to use pixi-sound with requirejs you have to specify its dependencies manually with shim like this

requirejs.config({
	paths: {
		'pixi': '../node_modules/pixi.js/dist/pixi.min',
		'pixi-sound': '../node_modules/pixi-sound/dist/pixi-sound'
	},
	shim: {
		'pixi-sound': {
			deps: ['pixi']
		}
	}
})

[koutoftimer]

@bigtimebuddy Perhaps, this can be added to wiki or readme in order to prevent similar issues from creating.

[bigtimebuddy]

Will do! Thanks for investigating.

[bigtimebuddy]

Added https://github.com/pixijs/pixi-sound/wiki#amd-integration