Enhanced welcome page

[danrubel]

Per discussion with Josh Teague and others, it would be nice to have an enhanced welcome that appears when editor is first launched. This page would provide a brief introduction, one-click-load samples, followed by links for more information. The layout might look something like this

   ... brief explanatory text with link(s) to "what is dart", etc

   -------------------------------------------------------------------------------

   Samples: (click to load)

   [ sample #­1 ] [ sample #­2 ] [ sample #­3 ] [ sample #­4 ]

   -------------------------------------------------------------------------------

   ... more information and links to FAQ, dartlang.org, etc

Each sample would be represented by a name and 512 x 512 pixel image. Hovering over the image would display a paragraph describing the sample. Clicking on the name or image would load the sample into Dart Editor.

[scheglov]

Set owner to @scheglov.
Added Accepted label.

[bwilkerson]

If we display samples on the welcome page, then that would also address http://code.google.com/p/dart/issues/detail?id=367.

[danrubel]

Issue #367 has been merged into this issue.

[scheglov]

https://chromiumcodereview.appspot.com/9335002

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Added Started label.

[scheglov]

Added Fixed label.