[2.0.1] Implement error collection for RemoveForeignElements.

- Register Generator context variable.
- Implement special substitutions for error collector.
- Also sort by order the errors came in.
- Fix line number determination bug in Lexer::create().
- Remove vestigial variables.
- Force all tag transforms to use copy(), implement serialize, unserialize algorithm for copy() in tokens.

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1238 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/Generator.php

@@ -46,7 +46,8 @@ HTMLPurifier_ConfigSchema::define('Output', 'Newline', null, 'string/null', '
 
 /**
  * Generates HTML from tokens.
- * @todo Create a configuration-wide instance that all objects retrieve
+ * @todo Refactor interface so that configuration/context is determined
+ *     upon instantiation, no need for messy generateFromTokens() calls
  */
 class HTMLPurifier_Generator
 {