smarty/TODO

* Ability to load multiple sections in one {config_load ...}
* do away with Smarty.addons.php and make drop-in plugin directory for
  functions and modifiers
* handle asp style tags in $php_handler
* correctly capture nested php tag syntax in templates:
  <?php echo "<?php exit(); ?>"; ?>
* think about passing default structures to includes, i.e. {include
  default=$foo}, then using $bar in included template, instead of $foo.bar
* support implementations of prefiltes, mods, and others as class methods.
* possibly implement default modifiers that apply to variables upon display
* possibly implement undefined template tags custom handling
* think about possibility of supporting something like {$data[foo].$key[bar]}
* allow {custom} .. {/custom} style of custom functions
* ability to concatenate values/strings together
* fix all E_NOTICE warnings