Tidy up and improve Vector class memory usage (#2558)

This PR follows on from #2556 to reduce memory usage and performance when Vector is used with simple (scalar) values.
Additional tests added.

Sming/Wiring/WHashMap.h

@@ -32,6 +32,7 @@
 #include <iterator>
 #include <cstdlib>
 #include "WiringList.h"
+#include "Print.h"
 
 /**
  * @brief HashMap class template
@@ -89,6 +90,15 @@ template <typename K, typename V> class HashMap
 			return &v;
 		}
 
+		size_t printTo(Print& p) const
+		{
+			size_t n{0};
+			n += p.print(k);
+			n += p.print(" = ");
+			n += p.print(v);
+			return n;
+		}
+
 	private:
 		const K& k;
 		Value& v;
@@ -285,7 +295,7 @@ template <typename K, typename V> class HashMap
 
 	bool allocate(unsigned int newSize)
 	{
-		return keys.allocate(newSize, K{}) && values.allocate(newSize, nil);
+		return keys.allocate(newSize) && values.allocate(newSize);
 	}
 
 	/**