Fix bug in bro-cut when separator is not hexadecimal

Bro-cut was unable to process log files that had a literal character (instead
of a hexadecimal code) in the "#separator" line of the log file.  For
example, if a log file had a comma as the separator then bro-cut would
show either an error message or just blank lines, depending on the bro-cut
options being used.
Fix bug in bro-cut output of "#types" header line

Fixed a bug in bro-cut that could occur if both a time conversion option was
selected and a show header (-c or -C) option was selected.  In that
case, if the column number of the timestamp field in the log didn't match
the column number of the timestamp field on the command-line, then bro-cut
would not produce the correct output of the "#types" header line (it would
replace the wrong field with the string "string").  The fix for this bug
is to use the correct index value in the "times" array (the index must be
the column number in the log file).
Fix bug in bro-cut when log file has missing field

When bro-cut is processing multiple log files, then each time a log file
header is processed, bro-cut needs to clear the "columns" array, otherwise
there could be entries from a previous log file for fields that don't
exist in the current log file, which results in duplicate output columns
with no warning to the user.

This fix enables bro-cut to consistently output the "unknown field" error
message regardless of the order in which it processes such log files.
Fix bug in bro-cut when duplicate fields are specified

When duplicate field names were specified as bro-cut command-line parameters,
then bro-cut was producing bad output, because two identical column names
are the same index in the "idx" array, and so then the "columns" array
would have one undefined element.  Fixed by checking for this condition
and showing the user an error message.
Add more tests of bro-cut
Merge remote-tracking branch 'origin/fastpath'

* origin/fastpath:
  Add more tests of bro-cut
  Fix bug in bro-cut when duplicate fields are specified
  Fix bug in bro-cut when log file has missing field
  Fix bug in bro-cut output of "#types" header line
  Fix bug in bro-cut when separator is not hexadecimal