Streaming I/O and support of named pipes (#570)

* added streaming i/o for scripting, and a byteutil.get_size function

* added i/o stream class, also added named pipes support on lua side via ffi

* added constant file.named_pipes_prefix

* added buffered and yield modes for io_stream

* added new time function for work with UTC - utc_time, utc_offset, local_time

* docs updated

* constant pid moved to os.pid

* now gmtime_s and localtime_s used only in windows

src/logic/scripting/descriptors_manager.hpp

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+#include <optional>
+#include <string>
+#include <istream>
+#include <ostream>
+
+#include "io/io.hpp"
+
+namespace scripting {
+
+    struct StreamDescriptor {
+        std::unique_ptr<std::istream> in;
+        std::unique_ptr<std::ostream> out;
+    };
+
+    class descriptors_manager {
+    private:
+        static std::vector<std::optional<StreamDescriptor>> descriptors;
+
+    public:
+        static std::istream* get_input(int descriptor);
+        static std::ostream* get_output(int descriptor);
+
+        static void flush(int descriptor);
+
+        static bool has_descriptor(int descriptor);
+
+        static bool is_readable(int descriptor);
+        static bool is_writeable(int descriptor);
+
+        static void close(int descriptor);
+        static int open_descriptor(const io::path& path, bool write, bool read);
+
+        static void close_all_descriptors();
+    };
+}