Add Import format reader

[nichtich]

In continuation of #128 add PICA::Parser::Import based on https://wiki-cbs.oclc.org/wiki/images/Software_for_Data_Import.pdf.

[nichtich]

Current workaround:

#!/usr/bin/env perl
use v5.14.1;
use Encode;

# Convert PICA+ export format to normalized PICA+ with valid UTF-8

# Input format:
# - each record starts with an empty line and a line with \x1D
# - each field is one line, started with \x1E

while (<>) {
    chomp;
    next unless $_;    # ignore empty lines
    if ( $_ eq "\x1D" ) {
        say "" if $. > 2;    # start of next record
    }
    else {
        if ( $_ =~ /^\x1E[012][0-9][0-9][A-Z@]/ ) {
            my $field = substr $_, 1;

            # invalid UTF-8 => U+FFFD (Unicode REPLACEMENT CHARACTER)
            my $bytes = encode( 'UTF-8', decode( 'UTF-8', $field ) );
            if ( $field ne $bytes ) {
                warn "$.: invalid UTF-8\n";
            }

            print $bytes, "\x1E";
        }
        elsif ( $. > 2 ) {    # empty line after record
            say "$.: '$_'\n";
        }
    }
}

# newline after last record
say "";

[nichtich]

Implemented in release 2.10 (not released yet).