Misc small fixes to suppress warnings.

Code should now be clean with msvc /W4 and gcc /Wall /Wextra -pedantic with the exception of one deliberate warning in one test.

[SVN r57510]

numeric_cast_test.cpp

@@ -28,7 +28,7 @@ using namespace boost;
 using std::cout;
 
 
-int test_main( int argc, char * argv[] )
+int test_main( int , char * [] )
 {
 
 #   ifdef NDEBUG