Export commands deprecated

- Provided examplars of export commands re-implemented using the new
  _query command.
- Implemented export-xml.pl, export-xml.py, export-xml.rb.
- Implemented export-csv.pl.
- Implemented export-yaml.pl.
- Implemented export-ical.pl.

scripts/add-ons/export-csv.pl

@@ -0,0 +1,70 @@
+#! /usr/bin/perl
+################################################################################
+## taskwarrior - a command line task list manager.
+##
+## Copyright 2006 - 2011, Paul Beckingham, Federico Hernandez.
+## All rights reserved.
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 2 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+## FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, write to the
+##
+##     Free Software Foundation, Inc.,
+##     51 Franklin Street, Fifth Floor,
+##     Boston, MA
+##     02110-1301
+##     USA
+##
+################################################################################
+
+use strict;
+use warnings;
+use JSON;
+
+# Use the taskwarrior 1.9.4+ _query command to issue a query and return JSON
+my $command = '/usr/local/bin/task _query ' . join (' ', @ARGV);
+
+# Generate output.
+print "'uuid','status','tags','entry','start','due','recur','end','project',",
+      "'priority','fg','bg','description'\n";
+
+for my $task (split /,$/ms, qx{$command})
+{
+  my $data = from_json ($task);
+
+  print "'$data->{'uuid'}',",
+        "'$data->{'status'}',",
+        "'", (exists $data->{'tags'} ? join (' ', @{$data->{'tags'}}) : ''), "',",
+        "'$data->{'entry'}',",
+        "'", ($data->{'start'}    || ''), "',",
+        "'", ($data->{'due'}      || ''), "',",
+        "'", ($data->{'recur'}    || ''), "',",
+        "'", ($data->{'end'}      || ''), "',",
+        "'", ($data->{'project'}  || ''), "',",
+        "'", ($data->{'priority'} || ''), "',",
+        "'", ($data->{'fg'}       || ''), "',",
+        "'", ($data->{'bg'}       || ''), "',",
+        "'$data->{'description'}'",
+        "\n";
+
+  # Note that this format ignores:
+  #   wait
+  #   until
+  #   annotations
+  #   mask
+  #   imask
+}
+
+exit 0;
+
+################################################################################
+