Fix order of amendments in main motion view

[bspekker]

Describe the bug
If amendments have no number and are depicted in the main motion, they are shown in the order of the sequential numbers. That's no good.

How to Reproduce

1. create a motion with at least two paragraphs
2. create an amendment in the last paragraph (don't change the state so it has no automatically assigned number!)
3. create an amendment in the first paragraph (don't change the state so it has no automatically assigned number!)
4. go to the main motion and select "show all changes"
   -> the order of the amendments is wrong: the amendment to the first paragraph is shown below the amendment to the last paragraph

Example:

Expected behavior
The amendments are all shown at the correct paragraph.