Function tripNew

tripNew(json?): void
Start a new trip. Erase everything.
Parameters
- json: {
  promptIfDirty: boolean;
  removeExistingRoute: boolean;
  } = ...
  - promptIfDirty: boolean
    boolean: Show a confirmation dialog.
  - removeExistingRoute: boolean
    boolean: If true or missing, remove existing routes, markers, and tracks.
Returns void
Example
```
// Erase everything with no prompt
{promptIfDirty : false, removeExistingRoute : true}
```