New class template which extends regexp.

Loads the file from templates directory, adding the .tpl extension.

This file is then used to construct a regular expression.

__set() method is used to replace()-with():
$template->title = 'Hello World' does $template->replace('%title')->with(
'Hello World')

set() method (no '__') accepts an array and replaces key with value.
$template->set(['title' => 'Hello World']) does
$template->replace('%title')->with('Hello World')

out() method echos $template->execute(false), and clears replacements.
execute(false) executes the replacement, but does not update the source
Added boolean $update to execute() method.

If not set or true, the expression will execute, updating the source.
If set and false, the expression will execute leaving the source.
Added template for blog posts to be used with template class.
Use template file and class to create blog posts from database.
Removed $encloser and use '%' by default since it wouldn't be supported by __set()
Use static template::load() instead of new template()