quoting:

  in non-strict mode, messages don't require a blank line at the end
  with a missing end-terminator. A single newline is sufficient now.

  Handle trailing whitespace at the end of a boundary. Had to switch
  from using string.split() to re.split()

  Handle whitespace on the end of a parameter list for Content-type.

  Handle whitespace on the end of a plain content-type header.

Specifically,

get_type(): Strip the content type string.

_get_params_preserve(): Strip the parameter names and values on both
sides.

_parsebody(): Lots of changes as described above, with some stylistic
changes by Barry (who hopefully didn't screw things up ;).