ghci: load modules with settings
Motivation
Using multiple packages, some are using NoImplicitPrelude
with default-extensions and some are not, making it
impossible to load those into one ghci session.
See https://github.com/commercialhaskell/stack/issues/2173#issuecomment-240403578
Proposal
Allow specifying settings (extensions) when loading modules, remember them so that subsequent :reload
works as expected.