Abstract methods:

• __construct() - Constructor for template object
• assign(parameter) - Assign template vars to values. As a parameter is an array of pairs 'template_value_name'=>'value'.
• display(parameter) - Display template. As a paremeter use template name.
• template_exists(parameter) - check if template exists. As a parameter is a template's name.
• setTemplateDir(parameter) - set the default template system directory. As a parameter is directory's name.