STYLE: avoid unrestricted dictionary lookup in randomProcesses, waveModels

- ref issue #762

STYLE: consistency in file vs files for pointNoise and surfaceNoise

- use "files" when available, fallback to "file" otherwise.

src/randomProcesses/noise/noiseModels/noiseModel/noiseModel.C

@@ -183,12 +183,6 @@ Foam::noiseModel::noiseModel(const dictionary& dict, const bool readFields)
 }
 
 
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-Foam::noiseModel::~noiseModel()
-{}
-
-
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 bool Foam::noiseModel::read(const dictionary& dict)