Implements pedestrian crossing or remove associated icon file

[Ettapp]

Currently the file "passage.png" isn't used anywhere.

@jcavat What we should do ?

[jcavat]

Can you give me the link please

[Ettapp]

https://github.com/ABAPlan/abaplan-core/blob/master/src/app/editor/toolbar/img/passage.png

[Ettapp]

Must be an old asset, the pedestrian crossing is already implemented with this image: https://github.com/ABAPlan/abaplan-core/blob/master/src/app/editor/toolbar/img/pedestrian.png

The other pedestrian asset is useless too, the pull request #130 remove it.