Improve I18N Issues (Based on 1.3)

I fully localized this great plugin to zh_TW, and I found some I18N issues.

Modified codes are listed as the following.

image-licensing-schema.php Line 174 (Typo)

<?php esc_html_e( 'Public Domain (CC0)', 'image-licensing-schema' ); ?>

image-licensing-schema.php Line 309 (Combine two parts to complete sentence)

<?php printf(esc_html__( 'Choose an existing page of your site %1$sor create a new one%2$s', 'image-licensing-schema' ),'<a href="' .admin_url( '/post-new.php?post_type=page' ) . '" target="_blank" class="imalisch_external_link">','</a>'); ?>

image-licensing-schema.php Line 405 (Typo)

<label for="imalisch_settings_cc0_<?php echo $i; ?>"><?php esc_html_e( 'CC0 Public Domain', 'image-licensing-schema' ); ?></label>