Feature Pulled

- Removed the feature that allows commands to be piped in to stdin,
  and appended to any existing command line.  This feature is
  conditionally compiled, controlled by the FEATURE_STDIN define in
  main.h
- Many unit tests contained "echo '-- y'", and now use "echo 'y'"
  because the '--' is no longer supported on stdin.
- Thanks to the IRC team for testing, including Bryce Harrington,
  Sam Stuck, Owen Clarke, Greg Grossmeier.

test/bug.634.t

@@ -45,7 +45,7 @@ if (open my $fh, '>', 'bug.rc')
 qx{../src/task rc:bug.rc add Test};
 
 # Result: Attempt to undo add with confirmation=off
-my $output = qx{echo '-- n' |../src/task rc:bug.rc rc.confirmation=off undo};
+my $output = qx{echo 'n' |../src/task rc:bug.rc rc.confirmation=off undo};
 unlike ($output, qr/Are you sure/ms, 'Undo honours confirmation=off.');
 
 # Cleanup.