cpp_headers: Renamed C++ headers from .h -> .hpp

To make room for UPM C and C++ sensor code to coexist, all UPM
C++ headers have been renamed from h -> hpp.  This commit contains
updates to documentation, includes, cmake collateral, examples, and
swig interface files.

    * Renamed all cxx/cpp header files which contain the string
    'copyright intel' from .h -> .hpp (if not already hpp).

    * Replaced all references to .h with .hpp in documentation,
    source files, cmake collateral, example code, and swig interface
    files.

    * Replaced cmake variable module_h with module_hpp.

    * Intentionally left upm.h since this file currently does not
    contain code (documentation only).

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/nrf24l01/Callback.hpp

@@ -0,0 +1,22 @@
+#pragma once
+
+#if defined(SWIGJAVA) || defined(JAVACALLBACK)
+class Callback
+{
+  public:
+    virtual ~Callback()
+    {
+    }
+    virtual void run()
+    { /* empty, overloaded in Java*/
+    }
+};
+
+
+static void generic_callback (Callback* callback)
+{
+    if (callback == NULL)
+        return;
+    callback->run();
+}
+#endif