Incompatible changes to Monomer interfaces. This branch does not work! - (!!) only changed allpy._monomer, not uses - (!!) removed (temporarily) classes for specific monomer types (DNAMonomer, etc) - refurbished allpy.data.AAcodes to allpy.data.codes with much cleaner interface - refurbished allpy._monomer for simplicity and more friendly interface Now it will (someday) be possible to say: a = Monomer.from_name("alanine") b = protein.Monomer.from_code1("a") c = protein.MonomerType.from_code3("ala") d = dna.Monomer.from_code3("DA") but impossible to say: d = protein.Monomer.from_code3("DA")