code128: Simplify handling of non-data characters
code128: Simplify handling of non-data characters

bwipp/postscriptbarcode,bwipp/postscriptbarcode,bwipp/postscriptbarcode,bwipp/postscriptbarcode,bwipp/postscriptbarcode,bwipp/postscriptbarcode,bwipp/postscriptbarcode,bwipp/postscriptbarcode