Build a state machine for the main code

[lucaslealvale]

This state machine is supposed to be able to deal with errors between the communication of the tag and the reader.
For example, if the flag of decoder error raises it should be properly treated and dealed with
So a State machine should be able to alternate between sending, receving of commands and also to deal with timeouts and errors

21b-indago-rfid-conformance-tester/fpga/software/rfid_test/main.c

Line 21 in f95954a

int main()