Bug 9265 - Switch to HTML5 doctype in OPAC and staff client

Bug 9265 - Switch to HTML5 doctype in OPAC and staff client

This patch replaces the XHTML DOCTYPE with an HTML5 one. The HTML5
validator seems to be significantly different than the XHTML one,
so I'm seeing lots of new errors. This patch includes corrections
for one: Deprecation of the "language" attribute of <script>
tags.

To test, view pages in the OPAC and staff client. They should
appear as normal. Numerous validation follow-ups will be required,
but I suggest these be handled incrementally.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
test on some intranet pages and I found no regression. (chromium and
firefox).
The w3c page about the doctype: http://www.w3.org/TR/html5-diff/#doctype

Signed-off-by: Mason James <mtj@kohaaloha.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>