Fully validate ModeS preamble before trying ModeA

[kad]

ModeA messages are shorter than ModeS and thus sometimes broken ModeS messages are detected as bogus ModeA messages. To eliminate that, I think it would better idea to see if preamble is actually ModeS, even broken one, and only then try to see if it would match as ModeA.

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This change is

[steel101]

just inserted the code in to my fork it has this and plane count and plane count in title and signal and settings page demo at http://bitropy.net:8080