Change somfy_iohc to recognize more messages

[mtdcr]

• Messages can be as short as 11 bytes.
• Message length has 5 bits instead of 4.
• Flags were assumed to be constant, causing two-way remotes not to get recognized.
• The message type (command id) is not indicated by the 1st but the 9th byte.
• Trailing bytes were not removed, leading to invalid length and failing CRC.
• Sequence numbers and MAC are limited to authenticated one-way frames.

This was briefly tested using both one- and two-way remotes.

[zuckschwerdt]

Great stuff, looks good. Thanks!

[mtdcr]

Thanks for you review! I added another commit reintroducing the use of the MIN macro. I'll stop here, because I'm not interested in discussing style preferences of yet another project just to contribute a single patch. You can modify it to suit your needs, if you like to.

[zuckschwerdt]

not interested in discussing style preferences of yet another project

Fair enough. The work analyzing and coding the protocol is appreciated.

TBH style preferences here are mostly "same dumb simple in all decoders" -- with ~200 decoders any "smart" or "neat" will cause headache when e.g. refactoring with some regex is needed.

[Velocet]

@mtdcr / @zuckschwerdt You both should have a look at iown-homecontrol The protocol is mainly deciphered and the „encryption“ is broken and documented. You will find all relevant info there.