Add route type filter in admin area post listing

[alexboia]

Is your feature request related to a problem? Please describe.
When listing posts in the admin area, I would like to be able to filter by route type (bike/train ride/hiking...)

Describe the solution you'd like
Just add a route type drop-down in the admin area that contains the route types.
If possible, make it multi-select.
Result listing must not include posts which do not have an explicit route type attached to them.
In addition to that, a column needs to be added in the admin post listing to indicate route type, if set.