Forcing all links to use https


I would like to know if there is a way to force all the links in my Plone site to use https, instead of http. I'm using Plone 4.
For example:
<a href="">YouTube</a>
instead of
<a href="">YouTube</a>

I appreciate any help


In the past I've unleashed on some sites, but that was for Plone 4/Archetypes.
According to some work has been done on that, but I don't think that's finished.
It would certainly be a useful product to have working on Plone5