typeIOobject: Template typed form of IOobject for type-checked object file and header reading

used to check the existence of and open an object file, read and check the
header without constructing the object.

'typeIOobject' operates in an equivalent and consistent manner to 'regIOobject'
but the type information is provided by the template argument rather than via
virtual functions for which the derived object would need to be constructed,
which is the case for 'regIOobject'.

'typeIOobject' replaces the previous separate functions 'typeHeaderOk' and
'typeFilePath' with a single consistent interface.

applications/utilities/preProcessing/applyBoundaryLayer/applyBoundaryLayer.C

@@ -174,7 +174,7 @@ int main(int argc, char *argv[])
         epsilon.write();
 
         // Turbulence omega
-        IOobject omegaHeader
+        typeIOobject<volScalarField> omegaHeader
         (
             "omega",
             runTime.timeName(),
@@ -184,7 +184,7 @@ int main(int argc, char *argv[])
             false
         );
 
-        if (omegaHeader.typeHeaderOk<volScalarField>(true))
+        if (omegaHeader.headerOk())
         {
             volScalarField omega(omegaHeader, mesh);
 
@@ -202,7 +202,7 @@ int main(int argc, char *argv[])
         }
 
         // Turbulence nuTilda
-        IOobject nuTildaHeader
+        typeIOobject<volScalarField> nuTildaHeader
         (
             "nuTilda",
             runTime.timeName(),
@@ -212,7 +212,7 @@ int main(int argc, char *argv[])
             false
         );
 
-        if (nuTildaHeader.typeHeaderOk<volScalarField>(true))
+        if (nuTildaHeader.headerOk())
         {
             volScalarField nuTilda(nuTildaHeader, mesh);
             nuTilda = nut;