kdeFrameworks: fixup inputs and outputs

- Reduce environment pollution with a separate $bin output containing programs,
  plugins, and shared data. Libraries remain in $out and are not installed into
  the environment.
- Only propagate build inputs as required.

pkgs/development/libraries/kde-frameworks/kplotting.nix

@@ -9,5 +9,6 @@ mkDerivation {
     broken = builtins.compareVersions qtbase.version "5.6.0" < 0;
   };
   nativeBuildInputs = [ extra-cmake-modules ];
-  buildInputs = [ qtbase ];
+  propagatedBuildInputs = [ qtbase ];
+  outputs = [ "out" "dev" ];
 }