Unit Tests - color.disable color.pri config.obsolete

- Added unit tests to cover automatic colorization by priority.
- Added unit tests to cover automatic disabling of color when !isatty.
- Added unit tests to cover display of unsupported configuration
  variable in the 'version' report.
- Added support the '_forcecolor' configuration variable to allow the
  possibility of unit tests that test color support, yet redirect
  output to a file.  This configuration variable will not be
  documented.

src/tests/config.obsolete.t

@@ -0,0 +1,57 @@
+#! /usr/bin/perl
+################################################################################
+## task - a command line task list manager.
+##
+## Copyright 2006 - 2009, Paul Beckingham.
+## 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 Test::More tests => 5;
+
+# Create the rc file.
+if (open my $fh, '>', 'obsolete.rc')
+{
+  print $fh "data.location=.\n",
+            "foo=1\n";
+  close $fh;
+  ok (-r 'obsolete.rc', 'Created obsolete.rc');
+}
+
+# Test the add command.
+my $output = qx{../task rc:obsolete.rc version};
+
+like ($output, qr/Your .taskrc file contains these unrecognized variables:\n/,
+               'unsupported configuration variable');
+like ($output, qr/  foo\n/, 'unsupported configuration variable');
+
+# Cleanup.
+unlink 'pending.data';
+ok (!-r 'pending.data', 'Removed pending.data');
+
+unlink 'obsolete.rc';
+ok (!-r 'obsolete.rc', 'Removed obsolete.rc');
+
+exit 0;
+