Standardize pixel type descriptions.
Standardize pixel type descriptions.

Descriptions should now state more clearly that the number of bits
describes bits per channel, not total number of bits.

Descriptions are made to have the same format for easier comparison,
clearly stating each component by name, except for YCbCr,
which needs more care.

Chobbes/Juicy.Pixels,Chobbes/Juicy.Pixels,clinty/Juicy.Pixels,Twinside/Juicy.Pixels,Twinside/Juicy.Pixels,Twinside/Juicy.Pixels,clinty/Juicy.Pixels