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

res/modules/internal/stream_providers/file.lua

@@ -0,0 +1,17 @@
+local io_stream = require "core:io_stream"
+
+local lib = {
+    read = file.__read_descriptor,
+    write = file.__write_descriptor,
+    flush = file.__flush_descriptor,
+    is_alive = file.__has_descriptor,
+    close = file.__close_descriptor
+}
+
+return function(path, mode)
+    return io_stream.new(
+        file.__open_descriptor(path, mode),
+        mode:find('b') ~= nil,
+        lib
+    )
+end