Receive and transmit IR remote codes

[pythoncoder]

I have now produced a hopefully stable release. Any users are advised to update. These are the major changes:

• Support for the MCE protocol (as used to control Kodi etc).
• Improved docs.
• Bugfix to RC5X where polarity of extended bit was inverted (rx and tx). Also affects RC5.
• Bugfix to NEC transmitter where MSB of address was ignored.
• Transmitter now validates args and raises a ValueError if out of range.

There is limited support for capturing and replaying unknown IR sequences. This is not a universal remote control, for reasons explained in the docs. Tools are provided to help experimenters write code to receive, store and "blast" undocumented, proprietary protocols. This without establishing the protocol structure - a task which can be quite challenging.