esp8266/scripts/ntptime: Add simple NTP client.

.time() returns seconds since MicroPython epoch (2000-01-01 00:00UTC),
.settime() sends current system time, assuming UTC timezone.

esp8266/scripts/ntptime.py

+try:
+    import usocket as socket
+except:
+    import socket
+try:
+    import ustruct as struct
+except:
+    import struct
+
+# (date(2000, 1, 1) - date(1900, 1, 1)).days * 24*60*60
+NTP_DELTA = 3155673600
+
+def time():
+    NTP_QUERY = bytearray(48)
+    NTP_QUERY[0] = 0x1b
+    addr = socket.getaddrinfo('pool.ntp.org', 123)[0][-1]
+    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    s.settimeout(1)
+    res = s.sendto(NTP_QUERY, addr)
+    msg = s.recv(48)
+    s.close()
+    val = struct.unpack("!I", msg[40:44])[0]
+    return val - NTP_DELTA
+
+# There's currently no timezone support in MicroPython, so
+# utime.localtime() will return UTC time (as if it was .gmtime())
+def settime():
+    t = time()
+    import machine
+    import utime
+    tm = utime.localtime(t)
+    tm = tm[0:3] + (0,) + tm[3:6] + (0,)
+    machine.RTC().datetime(tm)
+    print(utime.localtime())