- Cosmetic: replace tabs with blanks, strip trailing white space,
and update copyright headers with spec-cleaner.

- Update base-compat to version 0.10.4.
## Changes in 0.10.4 [2018.07.03]
- Make more modules `Trustworthy`. In particular, fix a regression in which
`Prelude.Compat` was inferred as `Unsafe` by explicitly marking it as
`Trustwothy`.
## Changes in 0.10.3 [2018.07.02]
- Backport the proper fixity for `($!)`, which was accidentally omitted in
`base-compat-0.10.2`.
## Changes in 0.10.2 [2018.07.02]
- Sync with `base-4.12`/GHC 8.6
- Backport `RuntimeRep`-polymorphic versions of `($!)` and `throw` to
`Prelude.Compat` and `Control.Exception.Compat`, respectively
(if using `base-4.10`/GHC 8.2 or later).
- Introduce the `Data.Functor.Contravariant.Compat` module, which reexports
`Data.Functor.Contravariant` if using `base-4.12`/GHC 8.6 or later.
See `Data.Functor.Contravariant.Compat` in the corresponding
`base-compat-batteries` release for a version with a wider support window.
## Changes in 0.10.1 [2018.04.10]
- Add `Data.List.NonEmpty.Compat`.
- Reexport `(Data.Semigroup.<>)` from `Data.Monoid.Compat` back to `base-4.9`.
## Changes in 0.10.0 [2018.04.05]
- Sync with `base-4.11`/GHC 8.4
- Backport `Semigroup((<>))` to `Prelude.Compat`.
Note that the `Semigroup` class has only been in `base` since
`base-4.9`/GHC 8.0, so accordingly, this can only be backported back
to GHC 8.0. If you wish to have a version of `Prelude.Compat` that backports
`Semigroup` to older GHCs (by conditionally depending on the `semigroups`