Expose Data.Fixed.Fixed's constructor

Discussed on libraries@, and summarised in
http://www.haskell.org/pipermail/libraries/2012-December/019076.html
Clarify the wording of the 'insert' haddock; fixes #7421

Wording suggested by Bart Massey.
Fix Data.Fixed.Fixed's Read instance; fixes #7483
Remove unused import
Comment out IsEven, isEven, and friends, because the type is ambiguous

It will become un-ambiguous when Iavor teaches the type inference
engine to prove more things, but until then this stuff is not useful.
Merge branch 'master' of http://darcs.haskell.org//packages/base
Expose new threadWaitSTM functions in Control.Concurrent (see #7216).

Supports threadWaitReadSTM and threadWaitWriteSTM on Windows with the threaded runtime system.
Fix warnings
Fix ambiguity error on Windows

I assume that we only want to catch IOExceptions, as withThread does.
Fix warnings on Windows
Add Generic instances to GHC.Generics representation types
Temporary workaround for the broken AC_SYS_LARGEFILE in autoconf >= 2.68 (#7537)