Merge pull request #348 from bhaettasch/master

Tutorials: Improved IE compatibility
Add pickOnNav Flag to the Scene to disable picking during navigation
Fix for LOD computation
fixed audio clip playing on enabled set to true
Merge branch 'master' of https://github.com/x3dom/x3dom
fixed sound tutorial
tutorial fix
Add sortType and sortKey field to the MultiPart node
Add initialVisibility field to the MultiPart node
Improve PixelTexture caching and faster setPixel method
change behavior of explorationMode field, so that it only affects the left mouse button
change MultiPart behavior for an empty selection
cache PixelTextures per namespace
add MultiPart getIdList function
Merge branch 'master' of https://github.com/x3dom/x3dom
outsource the MultiPart Parts-object to a separate file
Modified the offset size value for the on the fly gradient calculation.
Mainly modifying the constraints of what should be a valid normal for the styles, modified to a more restrictive value. This constraint could be modified again on the future.
Merge pull request #354 from aarbelaiz/volren-minor-corrections

Some minor corrections for the volume rendering component
Make MultiPart compatible with fitAll + showAll and add a fitPart function