Revert owningTemplate hack from 39e3e3a6.

It is no longer needed now that we use DMD's model for determining
whether to emit templates. We might also be able to use the more
general tinst/minst machinery from DMD Git master if we ever need
something similar.
Merge pull request #730 from klickverbot/remove-owningtemplate

Revert owningTemplate hack from 39e3e3a6.