Image type definition abandoned; using only BoofCV data structures

* The color type field was abandoned.
* Only ImageUInt8 and MultiSpectral<ImageUInt8> are considered
as images.
* Basic functions to construct and get information from images.
core fns using protocol; removal of old code

* Common fns for MultiSpectral and ImageUInt8 are implemented via
protocols.
tests for the basic fns
fns to return a lazy seq from an image and to print its data
namespace to load and save images; handles BufferedImages too