ENH: improve objectRegistry functionality (issue #322)

- Recursive searching for objects within a registry is now optional
  (previous it was always done).

  A recursive search effectively blocks the construction of sub-sub-registries
  if their names are 'masked' by some parent level sub-registry with
  the same name! (BUG)

- Recursive search is now turned OFF by default, which makes it consistent
  with dictionary and probably causes the least number of surprises.

----
Various new convenience methods added:

lookupObjectRef()
- returns a non-const reference.
  For example,

      volScalarField& U = mesh().lookupObjectRef<volScalarField>("U");

  Instead of

      volScalarField& U = const_cast<volScalarField&>
      (
          mesh().lookupObject<volScalarField>("U")
      );

--
lookupObjectPtr()
- returns a const pointer, and nullptr on failure.
  For example,

      const volScalarField* Uptr = mesh().lookupObjectPtr<volScalarField>("U");
      if (Uptr)
      {
          const volScalarField& U = *Uptr;
          ...
      }

  Instead of

      if (mesh().foundObject<volScalarField>("U"))
      {
          const volScalarField& U = mesh().lookupObject<volScalarField>("U");
          ...
      }

--
lookupObjectRefPtr()
- returns a non-const pointer, and nullptr on failure.
  For example,

      volScalarField* Uptr = mesh().lookupObjectRefPtr<volScalarField>("U");
      if (Uptr)
      {
          volScalarField& U = *Uptr;  // use as reference
          (*Uptr) = ...;              // or use directly
      }

  Instead of

      if (mesh().foundObject<volScalarField>("U"))
      {
          volScalarField& U = const_cast<volScalarField&>
          (
              mesh().lookupObject<volScalarField>("U")
          );
      }

--
sortedNames()
- now works with template parameters and with regular expression
  matching as well.
  For example,

      wordList names  = mesh().sortedNames();
      wordList fields = mesh().sortedName<volScalarField>();

  Instead of

      wordList names  = mesh().sortedNames();
      wordList fields = mesh().names<volScalarField>();
      Foam::sort(fields);

--

applications/test/objectRegistry/Test-objectRegistry.C

@@ -76,9 +76,8 @@ void printRegistry
     Foam::label indent
 )
 {
-    hashedWordList regs = obr.names<objectRegistry>();
-    regs.sort();
     wordList names = obr.sortedNames();
+    hashedWordList regs = obr.sortedNames<objectRegistry>();
 
     std::string prefix;
     for (label i=indent; i; --i)
@@ -121,7 +120,8 @@ void printRegistry
         const word& name = regs[i];
         const objectRegistry& next = obr.lookupObject<objectRegistry>
         (
-            name
+            name,
+            recursive
         );
 
         os  << prefix.c_str()
@@ -158,13 +158,13 @@ int main(int argc, char *argv[])
         "skip",
         "skip some parts"
     );
-    // argList::validArgs.append("recursive (true|false)");
+    argList::validArgs.append("recursive (true|false)");
 
     #include "setRootCase.H"
     #include "createTime.H"
     #include "createPolyMesh.H"
 
-    // recursive = Switch(args[1]);
+    recursive = Switch(args[1]);
 
     const bool optMesh   = args.optionFound("mesh");
     const bool optSkip   = args.optionFound("skip");
@@ -183,7 +183,8 @@ int main(int argc, char *argv[])
         db.subRegistry
         (
             entryName,
-            true
+            true,
+            recursive
         );
     }
 
@@ -200,7 +201,8 @@ int main(int argc, char *argv[])
         const objectRegistry& subreg = db.subRegistry
         (
             regName,
-            true
+            true,
+            recursive
         );
 
         for (label j = 0; j < 3; ++j)
@@ -210,12 +212,14 @@ int main(int argc, char *argv[])
             subreg.subRegistry
             (
                 entryName,
-                true
+                true,
+                recursive
             );
             subreg.subRegistry
             (
                 "$" + entryName, // qualified to avoid collisions
-                true
+                true,
+                recursive
             );
         }
     }
@@ -231,7 +235,8 @@ int main(int argc, char *argv[])
         db.subRegistry
         (
             entryName,
-            true
+            true,
+            recursive
         );
     }
 
@@ -249,7 +254,8 @@ int main(int argc, char *argv[])
         const objectRegistry& subreg = db.subRegistry
         (
             regName,
-            false
+            false,
+            recursive
         );
 
         if (!optSkip)
@@ -261,7 +267,8 @@ int main(int argc, char *argv[])
                 subreg.subRegistry
                 (
                     entryName,
-                    true
+                    true,
+                    recursive
                 );
             }
         }