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");

applications/solvers/discreteMethods/molecularDynamics/mdEquilibrationFoam/readmdEquilibrationDict.H

@@ -12,7 +12,7 @@ IOdictionary mdEquilibrationDict
     )
 );
 
-scalar targetTemperature = readScalar
+scalar targetTemperature
 (
-    mdEquilibrationDict.lookup("targetTemperature")
+    mdEquilibrationDict.get<scalar>("targetTemperature")
 );