rviz plugin for /fix(sensor_msgs/NavSatFix) message visualization

1. get Google Static Map API key
   https://developers.google.com/maps/documentation/static-maps/get-api-key?hl=ja
2. paste API key to config/google_static_map_api_key.yaml like this
   

• fix
  • type:sensor_msgs/NavSatFix
  • gps sensor data

• None

• overlay_gps_display/google_static_map_api_key
  • type:string

• Topic: topic name
• Zoom: Google Static Map API Zoom parameter
• Width: map image width
• Height: map image height
• Scale: Google Static Map API Scale parameter
• History Length: trajectory length
• Map Type: Google Static Map API Map Type parameter
• Alpha: Alpha value of map image
• Position X: upleft X position of image
• Position Y: upleft Y position of image
• Message Per Plot: number of messages per single plot

• Google Static Map API limitation (2017/11/08)
  • normal API user (supported in this package)
    • 25000 requests in 24 hours
    • Maximum resolution 640 x 640
  • Google Maps APIs Premium Plan user (not supported in this package)
    • The ratio in accordance with the annual number of purchase
    • 2048 x 2048

this package is not support over 25000 access in 24 hours!!!!