BitSet building convenience

Allow set()/clear()/flip() to be chained.
Support c++11 initializer lists.

testApp/misc/testBitSet.cpp

@@ -23,10 +23,13 @@
 
 #include <pv/bitSet.h>
 #include <pv/serializeHelper.h>
+#include <pv/pvUnitTest.h>
 
 #include <epicsUnitTest.h>
 #include <testMain.h>
 
+namespace {
+
 using namespace epics::pvData;
 using std::string;
 
@@ -37,6 +40,18 @@ static string toString(BitSet& bitSet)
     return oss.str();
 }
 
+void testInitialize()
+{
+    testDiag("testInitialize()");
+#if __cplusplus>=201103L
+    testOk1(BitSet().size()==0);
+    testOk1(BitSet({}).size()==0);
+    testEqual(BitSet().set(1).set(5).set(500), BitSet({1, 5, 500}));
+#else
+    testSkip(3, "Not c++11");
+#endif
+}
+
 static void testGetSetClearFlip()
 {
     testDiag("testGetSetClearFlip... ");
@@ -292,9 +307,12 @@ static void testSerialize()
 #undef TOFRO
 }
 
+} // namespace
+
 MAIN(testBitSet)
 {
-    testPlan(87);
+    testPlan(90);
+    testInitialize();
     testGetSetClearFlip();
     testOperators();
     testLogical();