Remove <% and <script language="php"> tags

As per https://wiki.php.net/rfc/remove_alternative_php_tags.

Removes:
 * <% opening tag
 * %> closing tag
 * <%= short opening tag
 * /<script\s+language\s*=\s*(php|"php"|'php')\s*>/i opening tag
 * /</script>/i closing tag
 * asp_tags ini directive
Fix unused variable warning
Regenerate tokenizer data

Also fix the tokenizer_data_gen.sh script after 64bit changes.
Add UPGRADING stubs for a number of recent changes