Add option to disable generating ids

[fchasen]

Added an autoIds option in Renderer. Defaults to true.

Setting it to false in the Renderer or kramed.defaults will disable creating ids.

kramed.setOptions({
    autoIds: false,
    renderer: false // must be recreated by Parser to get options
});

Also adjusts the regex to require a space between content and the id declaration per
http://kramdown.gettalong.org/syntax.html#specifying-a-header-id

That space will be removed in the output:
# Header {#myid} -> <h1 id="myid">Header</h1>

Includes a few changes to pass renderer options to Parser and merge them in Renderer.