Merge pull request #187 from RickMohr/search-more-prominent

Make search tool more prominent
Improve plugin resizing

* Make plugin resizing immediate and continuous (rather than using the default dojo animation)
* Call new plugin method resize() when a plugin container is resized, so plugins have a chance to update themselves
* Layer selector plugin implements resize(), revealing more width as container is resized wider
* Clarify existing layer selector resizing by renaming previous resize() function to onContentSizeChanged() (and add some doc)