ENH: add error::master() static for low-level messages

- a Pstream::master with a Pstream::parRun guard in case Pstream has
  not yet been initialised, as will be the case for low-level messages
  during startup.

- propagate relativeName handling into IOstreams

src/OpenFOAM/db/dictionary/functionEntries/functionEntry/functionEntry.C

@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -71,7 +72,7 @@ Foam::functionEntry::functionEntry
 :
     primitiveEntry
     (
-        word(key+dict.name()+Foam::name(is.lineNumber())),
+        word(key + dict.name() + Foam::name(is.lineNumber())),
         readLine(key, is)
     )
 {}
@@ -106,9 +107,9 @@ bool Foam::functionEntry::execute
     {
         FatalErrorInFunction
             << "Unknown functionEntry '" << functionName
-            << "' in " << is.name() << " near line " << is.lineNumber()
-            << nl << nl
-            << "Valid functionEntries :" << endl
+            << "' in " << is.relativeName()
+            << " near line " << is.lineNumber() << nl << nl
+            << "Valid functionEntries :" << nl
             << executedictionaryIstreamMemberFunctionTablePtr_->sortedToc()
             << exit(FatalError);
     }
@@ -148,9 +149,9 @@ bool Foam::functionEntry::execute
     {
         FatalErrorInFunction
             << "Unknown functionEntry '" << functionName
-            << "' in " << is.name() << " near line " << is.lineNumber()
-            << nl << nl
-            << "Valid functionEntries :" << endl
+            << "' in " << is.relativeName()
+            << " near line " << is.lineNumber() << nl << nl
+            << "Valid functionEntries :" << nl
             << executeprimitiveEntryIstreamMemberFunctionTablePtr_->sortedToc()
             << exit(FatalError);
     }