frontend: Free parser-allocated memory after handling a command.
client: Added sdb_client_sockfd() function.

This function returns the file-descriptor associated with the client's network
socket.
frontend: Added missing 'break' in switch statement.

This bug caused a LIST command to be executed after each QUERY.

D'oh!
sysdb: Store a global input handler object in the input module.

… rather than in the scanner. All input related code should be in the input
module.