Follow up of #854846-4: Null returned by Json.

background: html generated by spip includes some tags and html attributes that ideally should be cleaned up in order to obtain a migration as clean as possible.

Tags and html attributes can be cleaned up after migation with regular expresions and update queries on the drupal database. It can also be done in the migration process, but it will slow it down much more.

Probably some work can also be done on the spip side with a skeleton and some filters. Additionally in spip 2 series some overrides can be done with global variables, example:

ecrire/inc/texte.php:           tester_variable('debut_intertitre', "\n<h3 class=\"spip\">");
ecrire/inc/texte.php:           tester_variable('fin_intertitre', "</h3>\n");

This can be overriden with:

$GLOBALS['debut_intertitre'] = "\n<h3>\n";

This override is already implemented in spip2drupal's mes_options.php, but probably some other attributes can be cleaned up. Recent spip 2.1 seems to provide more options for customization: http://www.spip.net/en_article4729.html