Apply actions to several gpx at once

[IdrissaD]

Now we have two types of actions:

• actions that apply only to the gpx selected
• actions that can be applied to all of the gpx (color, opacity, width)

It would be nice to have a third option, apply actions to several but not all gpx:

• delete several gpx at once
• apply a color to several gpx
• etc. We would need to multi select the gpx, for instance by holding Ctrl (I don't know it it's doable with the way the gpx layers are built).

[vcoppe]

Thank you for your suggestion, I have re-implemented the website from scratch and added that to the future version. You can check it out here: https://gpx.studio/gpx.studio/ and provide feedback on this new repository: https://github.com/gpxstudio/gpx.studio.