Design ideas about iterators

[Patrick Julien]

> > To store 16 bits use two quantum...
> > One RGBA pixel four (or eight) quantum.
>
> hum, yes but if we use two quantum to do a quantum16, we will have to write
> a brand new colorstrategy, but if we use template, we can share some code
> between colors strategy.

That is an incorrect assumption.  What you need is for the channel depth to be 
a property of the paint device instead of a compile time option.