cycle file

first try to make multi file posible
where is no brake between the files
i't might be a good idea  to empty "data" (data=data[:]) before the first read from the new file
to prevent a malformed  package (between the last magic of the old file and the first in the new) 

the usage of the program changed to 
./replay [-h] [-p=<port>] [-z=<Hz>] file1 file2 ...