All useless nodes are removed from the route.
Notes:
- If the node is of one of the following types, it is not removed:
- Directional node
- Port node
- Offset node
- Support node
- If the node is referred by:
- a branch: the node is removed and the branch refers to the previous node. The position of the branch remains the same.
- an insulation: the start extremity of the insulation will refer to the previous node and the end extremity to the next node. The length of the insulation remains the same.