ENH: avoid readScalar, readLabel etc from dictionary (#762, #1033)

- use the dictionary 'get' methods instead of readScalar for
  additional checking

     Unchecked:  readScalar(dict.lookup("key"));
     Checked:    dict.get<scalar>("key");

- In templated classes that also inherit from a dictionary, an additional
  'template' keyword will be required. Eg,

     this->coeffsDict().template get<scalar>("key");

  For this common use case, the predefined getXXX shortcuts may be
  useful. Eg,

     this->coeffsDict().getScalar("key");

src/waveModels/waveModel/waveModel.C

@@ -302,7 +302,7 @@ bool Foam::waveModel::readDict(const dictionary& overrideDict)
     readIfPresent("U", UName_);
     readIfPresent("alpha", alphaName_);
 
-    nPaddle_ = get<label>("nPaddle");
+    readEntry("nPaddle", nPaddle_);
     if (nPaddle_ < 1)
     {
         FatalIOErrorInFunction(*this)