Fix numerous VC-10 compiler warnings.

Rewrite ICU configuration to use the new Boost.Build configuration logic.

[SVN r61893]

example/grep/grep.cpp

@@ -13,9 +13,14 @@
 #include <fstream>
 #include <string>
 #include <vector>
-#include <boost/program_options.hpp>
 #include <boost/regex.hpp>
 
+#ifdef BOOST_MSVC
+#pragma warning(disable:4512 4244)
+#endif
+
+#include <boost/program_options.hpp>
+
 namespace po = boost::program_options;
 
 int after_context;