It would be nice to be able to override a single template without keeping a 
private copy of the entire template directory. 

a setup option like

   templatedirs => [ "my/dir", "/usr/share/ikiwiki/templates" ] 

ought to do the trick.

> Now that I look at the source, I see that ikiwiki already falls back to the 
> global dir when it cannot find a template. For me, this is good enough.
> And it is even documented in the man page. Sigh. I guess this could be 
> considered [[done]].  
