picimo custom elements

[spearwolf]

use the custom element api to create picimo based custom elements ...

<picimo>

    <picture-texture-atlas src="foo.json" name="foo"/>

    <picimo-scene width="1000" height="600" size="contain">

        <picimo-picture src="foo#bar" display-position="top: 0; left: 50%">

        <picimo-sprite-group texture-atlas="name" picimo-controller="MySpriteGroup"/>

    </picimo-scene>

</picimo>