Expose Copilot.Compile.Bluespec.External. Refs #36.

The non-public `Copilot.Compiler.Bluespec.External` module lives under a
`shared/` directory so that it be imported by both the library code and the
test suite code. This is a questionable design, as if the test suite needs to
use the code, then it should be exposed by the library.

This commit moves `Copilot.Compiler.Bluespec.External` from `shared/` to
`src/`, exposes the module as part of the public API, and removes the `shared/`
directory. As a result, the test suite can now import
`Copilot.Compiler.Bluespec.External` like it does other parts of the
`copilot-bluespec` API.

Author: RyanGlScott

copilot-bluespec.cabal

@@ -36,7 +36,7 @@ source-repository head
 
 library
   default-language        : Haskell2010
-  hs-source-dirs          : src, shared
+  hs-source-dirs          : src
 
   ghc-options             : -Wall
   build-depends           : base              >= 4.9    && < 5
@@ -48,12 +48,12 @@ library
                           , language-bluespec >= 0.1    && < 0.2
 
   exposed-modules         : Copilot.Compile.Bluespec
+                          , Copilot.Compile.Bluespec.External
 
   other-modules           : Copilot.Compile.Bluespec.CodeGen
                           , Copilot.Compile.Bluespec.Compile
                           , Copilot.Compile.Bluespec.Error
                           , Copilot.Compile.Bluespec.Expr
-                          , Copilot.Compile.Bluespec.External
                           , Copilot.Compile.Bluespec.FloatingPoint
                           , Copilot.Compile.Bluespec.Name
                           , Copilot.Compile.Bluespec.Representation
@@ -70,8 +70,6 @@ test-suite tests
   other-modules:
    Test.Copilot.Compile.Bluespec
 
-   Copilot.Compile.Bluespec.External
-
   build-depends:
       base
     , directory
@@ -91,7 +89,7 @@ test-suite tests
     , copilot-bluespec
 
   hs-source-dirs:
-    tests, shared
+    tests
 
   default-language:
     Haskell2010