Possibility to create multiple isochrones and adjust the options for each one individually

[amoncaldas]

Implement the possibility of creating multiple isochrones and also the possibility to adjust the options of each isochrone individually. As the isochrone service does not support a request for multiple isochrones having distinct options for each one, multiple requests have to be made. In this case, the app URL has to be synchronized with these isochrones and options. So changes in the app data flow and URL encoding and decoding will be necessary.

[Discussion about multiple isochrones - classic client x new client] The isochrones form on the classic client works like a template used to generate, and does not represent the isochrones on the view (you can not adjust an existing isochrone). But the directions/routing form is linked to the view state, so the user can adjust a route displayed on the view. If an isochrone F is generated using foot profile, with options F1, then an isochrone B with bike profile, with options B1 is generated and finally an isochrone C with options C1 is generated, the interface will have the data of the last isochrone generated and the profile and options used to generate isochrone F1 and B1 are "lost", not visible and can not be adjusted. Even if you have one single isochrone you can not adjust it. You have always to delete and generate a new one and the last one is always "overriding" the previous data on the URL and in the form. If you do not delete, but just "adjust" the values and hit generate an new isochrone will be rendered on top of the existing one.

All this aspects are related to the fact that the options and multiple isochrones are not synchronized with the app state and URL. It leads to confusion. The way the isochrones feature was implemented in the classic client allowed to have this generation of multiple isochrones using a template, but the fact that the interface works in a very different way in the same app (for directions/routing) is commonly not expected/desired. The thing is that the strategy used in the classic client was different. So we should plan this feature in a way that we keep it in line with the new app strategy and keep the same base UX across different features.