Image iterator

Containers:

• iterator, const_iterator, ... : à-la STL built-in iterators (dereferencing is not necessarily a Value)
• ConstRange : adapted from iterator (STLVector) or from the container (STLMap)
• ConstRange::ConstIterator, ::ConstReverseIterator -> "*" returns a value

for CSetValueImage

  * image.setValue(point,val)

for CImage

• OutputIterator (can be adapted from setValueImage)