Fixed tiny error in options.c and renamed protocol options

1) I forgot to set *optarg to NULL after freeing it. This caused a bug in the options lib as it is used in the sender. By not settings the *optarg to NULL, the options_parse function cannot be called subsequently as is done in pilight-send.
2) I renamed the impuls unit code to programcode and id to systemcode. Check the help for the new arguments.
3) I renamed the sartano unit code to unitcode and the id to systemcode. Check the help for the new arguments.
Merge branch 'memory' of https://github.com/pilight/pilight into memory