Add support for FSK9600 and FSK1200

[rnbokade]

Many hams are no using different off the shelf ics like rfm-22b and different Lora chips supporting fsk modes in their HABs, amateur satellites, other radios.
Can decoding facility for fsk generated from them be add to the program, which can later route the data to the ssdv decoder or forwarders etc. Mostly for standard speeds like 1200,2400,4800,9600 bps. An option to define length of preamble and syncword and syncword to look for, will be need though.