Version 3.1.9

This release:

• Keeps payloadAuto allocated until the destructor - thank you @LeeLeahy2 #75
• Adds the new configuration keys for HPS 1.40 - resolves #73
• Adds the new RAIL dynamic model for HPS 1.40 - resolves #74
• Adds full auto (periodic) support for UBX-SEC-SIG (Version 1 and 2) - resolves #71
  • Please see CallbackExample9_SEC_SIG for more details