Commit:
1. Modified spider_spi.c to spider_spi.cpp.
2. Use SPI.h library provide from arduino library.
3. Fix socket.h compile with armgcc cause conflict issue with FD define in socket.h.
4. Add #include <SPI.h> in each example file.
Commit...
1. Change CS enable and disable functions.
Re-write ntp.ino, caculate year, month and day.
Fix code and bugs.