add a button to load route from gpx file

[blaulan]

Thank you for contributing to the project!

I have one small suggestion regarding class usage and it would be cool if you could provide a GPX file for me to try out :)

I'm new to javascript and css, so feel free to change the code. I did a quick search and find a repository that provides sample gpx file: https://github.com/gps-touring/sample-gpx/blob/master/BrittanyJura/Alt_Portsmouth.gpx

[pujux]

The code is fine! 😄 Great work man, thank you very much!