Need protective namespace for common (proteinogenic) amino acids

Right now display names for motifs are auto-generated as first three capitalized alphanumeric characters of the full name. This can lead to confusing abbreviations, like MET for METhylation and ASP for both ASParagine and ASPartic acid. We need to create a protected namespace for proteinogenic amino acids and make sure other motifs will not have those three-letter abbreviations.