Add a --bus-sort option to the I/O placer
Add a --bus-sort option to the I/O placer

- This is useful to group bits of differently named buses by index
  e.g., a[0] b[0] c[0] a[1] b[1] c[1] instead of a[0] a[1] b[0] b[1] c[0] c[1]

efabless/openlane,efabless/openlane,efabless/openlane,efabless/openlane