Mutilingual fix

I had several issues generating the POT file

Line 41: '#title' => 'Watermark',
Should be: '#title' => t('Watermark'),

Line 101: '#title' => 'Apply watermark to the following images',
Should be: '#title' => t('Apply watermark to the following images'),

Line 172: drupal_set_message(t('Watermark applied to image: ') . $row->filename);
Should be: drupal_set_message(t('Watermark applied to image: %file', array( '%file' => $row->filename ) ) );

Line 266: drupal_set_message(t("Image file $file not found."), 'error');
Should be: drupal_set_message(t('Image file %file not found.', array( '%file' => $file ) ), 'error');

Line 287: drupal_set_message(t("Image file $file is an unsupported format type=$type."), 'error');
Should be: drupal_set_message(t('Image file %file is an unsupported format type=%type.', array( '%file' => $file, '%type' => $type ) ), 'error');

Line 295: drupal_set_message(t("Failed to create handle for image file $file via function $function."), 'error');
Should be: drupal_set_message(t('Failed to create handle for image file %file via function %function.', array( '%file' => $file, '%function' => $function )), 'error');

Attached is an pu to date "fr.po" with the above mentionned fixes.