Rename DataEntry -> Function1

Function1 is an abstract base-class of run-time selectable unary
functions which may be composed of other Function1's allowing the user
to specify complex functions of a single scalar variable, e.g. time.
The implementations need not be a simple or continuous functions;
interpolated tables and polynomials are also supported.  In fact form of
mapping between a single scalar input and a single primitive type output
is supportable.

The primary application of Function1 is in time-varying boundary
conditions, it also used for other functions of time, e.g. injected mass
is spray simulations but is not limited to functions of time.

src/postProcessing/functionObjects/utilities/setTimeStep/setTimeStepFunctionObject.H

@@ -44,7 +44,7 @@ SourceFiles
 
 #include "functionObject.H"
 #include "dictionary.H"
-#include "DataEntry.H"
+#include "Function1.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -71,7 +71,7 @@ class setTimeStepFunctionObject
             bool enabled_;
 
             //- Time step
-            autoPtr<DataEntry<scalar>> timeStepPtr_;
+            autoPtr<Function1<scalar>> timeStepPtr_;
 
 
         //- Disallow default bitwise copy construct