Add some kind of `bytepad()` function?

[trevorld]

• 'bdf' font needs bitmap widths of multiples of 8 so could have a function that auto pads 0s to the right to reach multiple of 8

  • Use 'bm_width()' to get width of bitmap
  • Use %% 8 to get its remainder and bm_extend() to the right

• pdfparser has this functionality https://font.tomchen.org/bdfparser_py/bitmap/#bytepad

• Not sure this would be all that useful unless we were to write native bdf font export capabilities

[trevorld]

Or perhaps just add a new argument to bm_extend() like bytepad?