Check for success in loadArrayBuffer's onload handler.
More reliably stretch the base layer over the poles.
Improve consistency of `load...` functions.

Also add additional tests for them.
Update CHANGES.md.
Merge pull request #439 from AnalyticalGraphicsInc/stretchBaseLayerOverPoles

More reliably stretch the base layer over the poles.
Merge pull request #438 from AnalyticalGraphicsInc/loadArrayBuffer

Check for success in loadArrayBuffer's onload handler.
Move gitignore for Thumbs.db to the root to get rid of two other gitignore files.
Do not unload tiles with transitioning imagery.
Add clear method to TileLoadQueue.

Also add tests for TileLoadQueue.
Rename removeTile to shouldRemoveTile.
Merge pull request #442 from AnalyticalGraphicsInc/tileReplacementQueue

Do not unload tiles with transitioning imagery.
Rename TileLoadQueue.js to TileLoadQueueSpec.js.
Use context.createSampler to create samplers.

Previously, ImageryLayer was building the object literal manually.
Merge pull request #444 from AnalyticalGraphicsInc/useCreateSampler

Use context.createSampler to create samplers.
Add doc for TileLoadQueue.clear.
Merge pull request #443 from AnalyticalGraphicsInc/tileLoadQueue

Add clear method to TileLoadQueue.
Work around Firefox beta/canary worker transferable object bug.

This addresses issue #408.
Merge pull request #445 from AnalyticalGraphicsInc/firefoxWorkerBug

Work around Firefox beta/canary worker transferable object bug.
Merge remote-tracking branch 'origin/master' into color
Additional cleanup, more to come.

1. Delete NamedColors.js and roll it into Color.js
2. Static colors are now actual color instances.
3. fromCssColorString now only takes one parameter and returns undefined for invalid colors.
4. Break out regular expressions and helper functions to be locally scoped.