retire some csv char based routines. (#790)

retire some csv char based routines. (#790)

* retire some csv char based routines.

The last csv_lineparse user, garmin_txt, is converted to csv_linesplit.

xcsv_parse_val converted to use csv_stringtrim(QString,QString,int),
eliminating the other overloads.

xcsv_parse_style_line parsing of FIELD_DELIMITER, FIELD_ENCLOSER,
RECORD_DELIMITER and BADCHARS updated to use the above overload of
csv_stringtrim.  FIELD_DELIMITER, FIELD_ENCLOSER and RECORD_DELIMITER
changed to trim, with a double quote enclosure,  before character substitution.
There was a subtle bug in csvs_stringtrim(char, char, int).  When trimming
a source that was all white space the first white space character would
be retained, while others would be trimmed.  This did occur with CRNEWLINE,
but the bug allowed other substitutions to work, e.g. SPACE, NEWLINE, TAB, CR.

A small bug in csv_stringclean was fixed.  If the to_nuke was empty an invalid
regular expression was created.

* save a few string conversions.

* and a few more conversions saved.

* review comments incorporated in garmin_txt reader.

* fix minor bug accumulating badchars.