ENH: provide HashTable::iterator::found() method

- This can be used as a convenient alternative to comparing against end().
  Eg,

    dictionaryConstructorTable::iterator cstrIter =
        dictionaryConstructorTablePtr_->find(methodType);

    if (cstrIter.found())
    {
        ...
    }
  vs.
    if (cstrIter != dictionaryConstructorTablePtr_->end())
    {
        ...
    }

applications/test/Map/Test-Map.C

@@ -22,10 +22,9 @@ License
     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
 Application
-    testMapIterators
+    Test-Map
 
 Description
-    For each time calculate the magnitude of velocity.
 
 \*---------------------------------------------------------------------------*/
 
@@ -39,9 +38,7 @@ using namespace Foam;
 
 int main(int argc, char *argv[])
 {
-    Map<bool> banana;
+    Map<bool> banana{{5, true}};
-
-    banana.insert(5, true);
 
     // Taking a const iterator from find does not work!
     // Also, fails later on op==
@@ -50,7 +47,7 @@ int main(int argc, char *argv[])
     // This works but now I can change the value.
     //Map<bool>::iterator bananaIter = banana.find(5);
 
-    if (bananaIter == banana.end())
+    if (!bananaIter.found()) // same as  (bananaIter == banana.end())
     {
         Info<< "not found" << endl;
     }
@@ -62,8 +59,7 @@ int main(int argc, char *argv[])
     // Same with STL
     Info<< "Same with STL" << endl;
 
-    std::map<label, bool> STLbanana;
+    std::map<label, bool> STLbanana{{5, true}};
-    STLbanana[5] = true;
     std::map<label, bool>::const_iterator STLbananaIter = STLbanana.find(5);
 
     if (STLbananaIter == STLbanana.end())

src/OpenFOAM/containers/HashTables/HashTable/HashTable.H

@@ -403,6 +403,10 @@ public:
 
               // Access
 
+                //- True if iterator points to a hashedEntry.
+                //  This can be used instead of a comparison to end()
+                inline bool found() const;
+
                 //- Return the Key corresponding to the iterator
                 inline const Key& key() const;
 

src/OpenFOAM/containers/HashTables/HashTable/HashTableI.H

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
-     \\/     M anipulation  |
+     \\/     M anipulation  | Copyright (C) 2017 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -257,6 +257,14 @@ Foam::HashTable<T, Key, Hash>::iteratorBase::increment()
 }
 
 
+template<class T, class Key, class Hash>
+inline bool
+Foam::HashTable<T, Key, Hash>::iteratorBase::found() const
+{
+    return entryPtr_;
+}
+
+
 template<class T, class Key, class Hash>
 inline
 const Key& Foam::HashTable<T, Key, Hash>::iteratorBase::key() const