[js] make _loadAjaxHtmlHead aware of mod_concat-like urls
_loadAjaxHtmlHead keeps track of already imported resources (js / css)
to make sure they're not included twice, but with mod_concat-like urls,
things get a bit more complicated :
if BASE_URL/data??foo.js,bar.js is already imported, then loading :
BASE_URL/data??bar.js,spam.js should only load spam.js
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s entity's classes"""