Only amd64 has an efficient implementation currently.

Moved the default case of genCCall64 out into a separate function

You can now say
    data {-# CTYPE "some_header.h" "the C type" #-} Foo = ...

I think it's rare that this will actually be needed. If the
header for a CAPI FFI import includes a
    void f(ctype x);
prototype then ctype must already be defined.

However, if the header only has
    #define f(p) p->j
then the type need not be defined.

But either way, it seems good practice for us to specify the header that
we need.

to emit kind constraints when decomposing an application.
Resulting code is actually shorter!

Also add notes about unsafeCoerce

The general thread here is to reduce use of ArgKind after
the type checker; it is so fragile!

This is the start of more global renaming

Conflicts:
	compiler/types/TyCon.lhs

I have forgotten what the original driver for this change was.
There is quite a bit of refactoring in TcCanonical; the rest
is minor.

This isn't really a forced change, but is a useful tidy-up

including (a) centralising Outputable.paBrackets
          (b) printing the quote on promoted TyCon/DataCon

And in particular we now have BOX :: BOX
See Note [SuperKind (BOX)] in TysPrim

For now, the syntax is
    type    {-# CTYPE "some C type" #-} Foo = ...
    newtype {-# CTYPE "some C type" #-} Foo = ...
    data    {-# CTYPE "some C type" #-} Foo = ...