Port to Python3, use PySerial, and package using distutils

[alexeicolin]

Packaging using distutils makes it easy to use this as a library in standalone projects that want to use the LCD display board. The projects can just import odroidshow and use Screen/ScreenContext.

PySerial is simpler and faster than going through 'echo' for every write. The default TTY config flags set by PySerial turned out to be fine, so no need for port_open.c either.