markdown: Treat external links differently from internal links
markdown: Treat external links differently from internal links

This commit make external links are opened new window or tab.

doortts/fork-yobi,yona-projects/yona,doortts/fork-yobi,yona-projects/yona,doortts/fork-yobi,bloodybear/yona,bloodybear/yona,doortts/fork-yobi,bloodybear/yona,yona-projects/yona,yona-projects/yona,bloodybear/yona