Merge "docs: lots of additions to the resources docs new drawable resources...

     * without resorting to another data structure.

     *

     * The specified key should be an id declared in the resources of the

     * application to ensure it is unique. Keys identified as belonging to

     * application to ensure it is unique (see the <a

     * href={@docRoot}guide/topics/resources/more-resources.html#Id">ID resource type</a>).

     * Keys identified as belonging to

     * the Android framework or not associated with any package will cause

     * an {@link IllegalArgumentException} to be thrown.

     *

<p>Here's a brief summary of each resource type:</p>

<div class="sidebox-wrapper">

<div class="sidebox">

<h2>{@code R.id} Is Not a Resource</h2>

<p>You will often use an {@code R.id} integer to handle {@link android.view.View} objects in

your UI. Although the {@code id} is a subclass of the {@code R} class, it is not considered a

"resource" because it is not a reference to an externalized application resource. The {@code id}

is simply a unique identifier that allows you to handle elements in your UI by instantiating

objects with {@link android.app.Activity#findViewById(int) findViewById()}.</p>

<p>For information about using {@code R.id} with your UI, see <a

href="{@docRoot}guide/topics/ui/declaring-layout.html#attributes">Declaring Layout</a>.</p>

</div>

</div>

<dl>

  <dt><a href="{@docRoot}guide/topics/resources/animation-resource.html">Animation Resources</a></dt>

    <dd>Define pre-determined animations.<br/>