Add fast_io::iomnp namespace for allowing user to do things like

using namespace ::fast_io::iomnp;

then it should be equivalent to
using namespace ::fast_io::io;
using namespace ::fast_io::mnp;

Author: trcrsired

examples/0002.a+b/base36_a+b_iomnp.cc

@@ -0,0 +1,9 @@
+#include <fast_io.h>
+
+int main()
+{
+	using namespace ::fast_io::iomnp;
+	std::size_t a, b;
+	scan(base_get<36>(a), base_get<36>(b));
+	println(base<36>(a + b));
+}

include/fast_io_legacy_impl/io.h

@@ -354,4 +354,10 @@ static_assert(device_error, "freestanding environment must provide IO device");
 
 } // namespace io
 
+namespace iomnp
+{
+using namespace ::fast_io::io;
+using namespace ::fast_io::mnp;
+} // namespace iomnp
+
 } // namespace fast_io