Can classinfo and typeinfo_struct be templates?

[dsimcha]

I've created and submitted to Bugzilla a patch that makes heap scanning in the
GC precise, provided that the GC is provided with the necessary information
about pointer offsets when memory is allocated.  (Bug 3643)  It also includes
templates for generating that information for arbitrary types at compile time.

>From what I understand, Walter does not want new to become a template.
Currently, new receives RTTI to figure out how to perform an allocation (see
lifetime.d in druntime).  The pointer offset information necessary for precise
heap scanning can't be generated from RTTI in its current form, only by hand
or from templates.

An elegant solution to this problem would be to make TypeInfo for structs and
ClassInfo templates instead so that the information could easily be placed
inside these classes at compile time.  Right now, it appears that the way that
TypeInfo and ClassInfo find out the information about the types they represent
is through magic embedded in the compiler.  If they were templates, it would
be much easier to extend them without hacking the compiler, both for precise
GC and for any other reason.