Fix the build on lts-12. (google#213)

* Update changelogs for next 0.3.* release.

For:
 - proto-lens-protoc-0.3.1.1
 - proto-lens-protobuf-types-0.3.0.2

* Fix build of proto-lens-0.3.* on lts-12. (google#211)

Also update `stack.yaml` to `lts-12.6` rather than a nightly.

The proto-lens-protoc-0.3.1.1 release had an upper bound
on `temporary` that was too restrictive.  Increase it,
and bump the version to `0.3.1.2`.

Also fix warnings and improve CI.  Turns out the Travis script wasn't robust enough and google#195 let through
some warnings.  I fixed the script and confirmed it now catches such
issues.

Also bumped the tutorial and bootstrap scripts to the same LTS
as the main build.

Changelog.md

@@ -7,6 +7,10 @@
   instances call `showMessageShort`.
 - Generate explicit `NFData` instances for each type.
 
+## v0.3.1.2
+- Bump the upper bound to `temporary-1.3`.
+- Fix warnings.
+
 ## v0.3.1.1
 - Fix management of generated files between Cabal components (#171).
 - Bump the lower bound on `base` to indicate we require `ghc>=8.0`.

src/Data/ProtoLens/Compiler/Definitions.hs

@@ -7,6 +7,7 @@
 -- | This module takes care of collecting all the definitions in a .proto file
 -- and assigning Haskell names to all of the defined things (messages, enums
 -- and field names).
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -39,7 +40,9 @@ import Data.Int (Int32)
 import Data.List (mapAccumL)
 import qualified Data.Map as Map
 import Data.Maybe (fromMaybe)
-import Data.Monoid
+#if !MIN_VERSION_base(4,11,0)
+import Data.Monoid ((<>))
+#endif
 import qualified Data.Semigroup as Semigroup
 import qualified Data.Set as Set
 import Data.String (IsString(..))