Added OGP setting function and added display items on photo page

【Contents of modification】
■Added OGP setting function to theme options (Facebook/Twitter)
■Added support for displaying tags on photo pages.

The following are the files that have been modified for this update.
【Corrected files】
admin/theme-options.php
functions.php
header.php
languages/en.mo
languages/en.po
photek.css
single-portfolio.php
style.css
【Added files】
taxonomy-portfolio-tag.php

For more information, please visit the PHOTEK (tcd024) download site for purchasers.