Fixed #5890 -- fixed the far edge-case of allowing constant strings inside

template template markers: we now treat embedded, escaped double quotes
consistently with constant string arguments to filters. Patch from Dmitri
Fedortchenko.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@6724 bcc190cf-cafb-0310-a4f2-bffc1f526a37