sample - adding link
partial solution for #718
Merge branch 'master' of github.com:AnalyticalGraphicsInc/cesium into jsdoc
fixed sample link
added source link to doc
Merge branch 'master' of github.com:AnalyticalGraphicsInc/cesium into jsdoc
Make sure root tiles are always marked rendered so they're not unloaded.
link opens in new tab and styled
Fixes #760 - Globe tiles disappear

For level zero tiles, the bounding sphere tends to be close to the center
of the Earth and not necessarily in a useful direction.  So using it for
the horizon occlusion point produced a pretty crappy point, which was then
considered very slightly not visible when the camera was tipped all the
way down by the pole.  I switched to computing the horizon occlusion point
based on the center of the tile used for RTC instead, which is pretty
close to the same for small tiles, but much better for big ones.
Add test for #760.
Merge pull request #761 from AnalyticalGraphicsInc/issue760

Fixes #760 - Globe tiles disappear
Merge pull request #756 from AnalyticalGraphicsInc/texturePingPong

Make sure root tiles are always marked rendered so they're not unloaded.
Merge pull request #742 from nobelium/jsdoc

Solution for "Add source file links to reference doc" - Issue #718
Merge remote-tracking branch 'origin/master' into issue746