where possible, store vertex colors as magnitudes

Matlab RGB color schemes have 64 discrete color levels, which leads to
loss of precision.
Fix bugs John found

Better parameter handling
compressed TRIB, remove camlight flicker

Trib format now compressed (half the disk space). Camlight now fixed to
object not view specific (less flicker).
camLight relative to object

reduce Flicker - light always above object, regardless of viewer
position.
addLayer-colorBrightness fix

Would fail if addLayer was asked to compute vertex brightness when
other layers were already open.