0.7.0

• Fix the incorrect maximum allowed time span for F-net (#65)
• get_selected_stations now returns a list of stations with station metadata
  information (#36)
• Refactor the _channel2pz() and _write_pz() functions to Channel.write_sacpz()
• Refactor the _get_channels function to win32.read_ctable()
• The win32.extrac_sacpz function now supports parallel data processing
• The with_pz parameter in win32.extract_sac() is renamed to with_sacpz
• The win32.extrac_pz() function is renamed to win32.extract_sacpz()
• Move the function Client.check_cmd_exists() to utils.check_cmd_exists()
• Move the function Client.check_package_release() to utils.check_package_release()
• Fix the "ssl.SSLError: [SSL: DH_KEY_TOO_SMALL] dh key too small" error