Tightened up nearest neighbor code.
Caching mapColor results.
Added a few tweaks to overlay.blendImages
Merge pull request #119 from tsherif/optimize-color-map

Optimize color map. Closes #113.
Use local variable default_camera_distance instead of magic number
Surface Viewer: replaced .zoom() method by property; zoom property is now absolute
Updated Surface example to use the zoom property
Merge pull request #121 from PaulMougel/surface-viewer-zoom-property

Surface viewer zoom: use absolute zoom property instead of relative zoom method. Closes #116.
VolumeViewer: Updating a panel.zoom property triggers the zoom event
Merge pull request #124 from PaulMougel/volume-viewer-zoom-property-trigger-event

VolumeViewer: Updating a panel.zoom property triggers the zoom event