Don't use Proxy in Data.Records

[konsumlamm]

Currently, Proxy is automatically imported (it's reexported by Data.Records, which is reexported by Mhs.Builtin). This is a problem when defining your own type called Proxy, as is the case in the pipes library.

To fix this, I tried to get rid of all Proxy usages in Data.Records. However, with this PR, building mhs currently fails (which is why this is a draft PR) with the following error:

"lib/System/IO/Error.hs": line 325, col 39: kind error: cannot unify Symbol and Type

The code in question is

ioeSetErrorType   ioe errtype  = ioe{ ioe_type = errtype }

I'm not sure what causes this error, although changing the kind signature of HasField and SetField to use Symbol instead of k :: Kind seems to fix it (this would be a departure from how GHC does it though).

[augustss]

It's a bug that Proxy is in scope without being imported.
I'll try to fix that instead.

[augustss]

The Prelude mistakingly re-exported Data.Records. Fixed 52f0cc7