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/lua/libs/libbyteutil.cpp

@@ -197,9 +197,16 @@ static int l_tpack(lua::State* L) {
     return pack(L, format, true);
 }
 
+static int l_get_size(lua::State* L) {
+    return lua::pushinteger(
+        L, static_cast<int>(calc_size(lua::require_string(L, 1)))
+    );
+}
+
 const luaL_Reg byteutillib[] = {
     {"pack", lua::wrap<l_pack>},
     {"tpack", lua::wrap<l_tpack>},
     {"unpack", lua::wrap<l_unpack>},
+    {"get_size", lua::wrap<l_get_size>},
     {NULL, NULL}
 };