AbsTemplate 介绍
Abstemplate 是一个超简单和轻量级的PHP模版引擎，只包含唯一的一个文件，就是基类。
You can set your own custom delimiters for variables to use inside template
files, use any type of templates you want (that is, the template files can
have any extension you want (be it .PHP, .inc, .tpl, etc…)), display
multiple templates per page, cache templates, and choose to assign the content
of a template to a variable and, when appropriate, just display its content.