ENH: add argList::optionCount method

- convenience for checking is any/all particular options have been
  specified. Eg,

  if (args.optionCount({"opt1", "opt2", "opt3"}) < 3) ...

applications/test/argList/Test-argList.C

@@ -58,6 +58,9 @@ int main(int argc, char *argv[])
 
     argList args(argc, argv);
 
+    Info<<"have: "
+        <<args.optionCount({"label", "scalar"}) << " options" << nl;
+
     label ival;
     scalar sval;
 

src/OpenFOAM/global/argList/argList.C

@@ -1283,6 +1283,37 @@ Foam::argList::~argList()
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+Foam::label Foam::argList::optionCount(const UList<word>& optionNames) const
+{
+    label n = 0;
+    for (const word& optName : optionNames)
+    {
+        if (options_.found(optName))
+        {
+            ++n;
+        }
+    }
+    return n;
+}
+
+
+Foam::label Foam::argList::optionCount
+(
+    std::initializer_list<word> optionNames
+) const
+{
+    label n = 0;
+    for (const word& optName : optionNames)
+    {
+        if (options_.found(optName))
+        {
+            ++n;
+        }
+    }
+    return n;
+}
+
+
 bool Foam::argList::setOption(const word& optionName, const string& param)
 {
     // Some options are always protected

src/OpenFOAM/global/argList/argList.H

@@ -302,6 +302,12 @@ public:
             //- Return true if the named option is found
             inline bool optionFound(const word& optionName) const;
 
+            //- Return how many of the specified options were used
+            label optionCount(const UList<word>& optionNames) const;
+
+            //- Return how many of the specified options were used
+            label optionCount(std::initializer_list<word> optionNames) const;
+
             //- Return an input token stream for the named option
             inline ITstream optionLookup(const word& optionName) const;