Predoc is a lightweight document format. We will also develop WYSIWIG mode for Emacs and other related tools.
Added `img', `a' tag input helper feature.
1. Supported `img' tag which recognize "http://" URL.
2. Supported "path/of/image/file.(jpg|png|bmp ... )" string convert into `img' tag.
3. Supported "http://host/path/of/contents... anchor-keyword" string convert into `a' tag.
