switch to exceptions package (0.4-0.6)

Conflicts:

	iteratee.cabal
	src/Data/Iteratee/Base.hs
	src/Data/Iteratee/IO/Handle.hs

Conflicts:

	iteratee.cabal
	src/Data/Iteratee/Base.hs
	src/Data/Iteratee/IO.hs
	src/Data/Iteratee/IO/Fd.hs
	src/Data/Iteratee/IO/Handle.hs
version 0.8.4.6