abc template: Template engine that replaces tags in PHP scripts

This class implements a template engine that replaces tags in PHP scripts.

It can load a template file which can be a PHP script which is executed when the template is loaded.

The loaded template is processed by replacing tags, which are named marks delimited by curly braces, by template variable values.

When template variable values which are arrays, the class iterates the template processing over all values.

The class can display the processed template as the current script output or return the resulting template string.