Filter duplicate ControlPath entries and skip all empty lines in config file

[dapimentel]

Thank you for this gem of a tool; however, in the event a user's ~/.ssh/config file contains multiple copies of the same ControlPath pattern across multiple remote host configurations, some additional filtering must occur within the config_control_path() function. If this additional filter is rejected, then such config file content will result in the following warning from the host_from_socket() function:

 ${YLW}WARNING: cannot match host from socket name${RST}

For example, consider the following ~/.ssh/config content with a repeated ControlPath pattern:

Host host1*
  PKCS11Provider /usr/lib64/opensc-pkcs11.so
  Hostname host1.example.com
  User arthur
  ControlMaster auto
  ControlPath ~/.ssh/sockets/%r@%h::%p
  ControlPersist 10h

Host rz*
  Hostname my-gate.example.com
  User arthur
  ControlMaster auto
  ControlPath ~/.ssh/sockets/%r@%h::%p
  ControlPersist 10h
  RequestTTY force

Host rzremote*
  RemoteCommand /home/arthur/passthru.sh rzremote.example.com