Fix filename truncation of multi-stage operations

__aucdtect():
  Fix truncation of filename, and the printing of an operation's
  progress.  Before each stage of a given operation, determine if a
  given operation's item/filename needs to be truncated.  This allows
  correct displays of operational items/status.

Documentation:
  Remove the determination of lines, and put exported declaration in
  line with other operations.

Minor tweaks as well.