[project @ 2000-11-20 14:48:52 by simonpj]

[project @ 2000-11-20 14:48:52 by simonpj]
When renaming, typechecking an expression from the user
interface, we may suck in declarations from interface
files (e.g. the Prelude).  This commit takes account of that.

To do so, I did some significant restructuring in TcModule,
with consequential changes and tidy ups elsewhere in the type
checker.  I think there should be fewer lines in total than before.