torrc path option for happy families key file

When implementing Happy Families for ansible-relayor I realized two issues I want suggest a change now that no tor release with happy families has been released yet:

• Unfortunately it is not possible to tell tor where to find the key file

• the idea was to copy the file only once per server because all tor instances need the same file

• but tor expects it to be in the keys folder, which requires the creation of many files/links instead of a single file

• the torrc configuration needs to be changed when changing the key, if the torrc were to point to the file the torrc file would not need any changes

background: relayor and families are primarily for operators running more than one tor daemon on a server for scalability reasons.

For relayor this problem is solvable due to automation but manually operated relays will be more affected by these limitations and these limits might increase the risk that relays are not properly configured.

Suggestions for improvements:

• allow configuring the path to the keys file with a torrc option - the option may be used multiple times
• make the FamilyID string optional in the torrc file