Avoid an error if the file extension is not recognized.
Show an error panel when a render loop error occurs.

Also use the same error panel to indicate when an error occurred when dropping a file into CesiumViewer.
Use error panel for errors instead of alert.
Log errors to console by default when showRenderLoopErrors is true.
Improve Polygon Triangulation Algorithm

This replaces the O(n^2) ear clipping algorithm with an O(nlogn) random
cut algorithm.
Follow JSHint coding standards
Use DeveloperError instead of throwing object
A bit of refactoring

- Added changes to CHANGES.md
- Renamed earClip2D to triangulate
- Changed applicable new methods to be private
A few more fixes

- Changed tests to use "triangulat"e instead of "earClip2D"
- Added a test case compliments of @hpinkos
- Made sure that intersection testing tests from first to last vertex
- Fixed the case of polygons that have a side that intersects with a
  vertex and added test case (algorithm now prunes unnecessary in-line
  triangle that is created)
Always another corner case...

- Deals with cut validation corner cases (see comments)
Adjust styling on error box.
Better error handling during widget startup.

Diff this change ignoring whitespace (on GitHub use ?w=1 on the URL).
Merge remote-tracking branch 'origin/master' into addErrorPanel
Merge remote-tracking branch 'origin/master' into addErrorPanel
Adjust CHANGES.md and allow errors to word-wrap.
Fix test which was failing do to CSS class name change.
Merge pull request #1063 from AnalyticalGraphicsInc/addErrorPanel

Show an error panel when a render loop error occurs.
Fail gracefully in IE

Fixes #1086
Merge branch 'master' of github.com:AnalyticalGraphicsInc/cesium
Fail the build when JSDoc fails.