Fix namespace list order

Runtime namespace lists were being expanded by adding list members to the end of the runtime ordered dict, which broke repeat-section override for list members (by overriding the intended override with the original), e.g.:
```
[runtime]
   [[m1,m2,m3]]
        title = the quick brown fox
   [[m2]]
        title = jumped over the lazy dog
```
(this should result in ```m2``` getting ```title = jumped over the lazy dog```).

This change fixes the problem by replacing the original dict with an expanded one with the right order (simpler, and in any case ordered dicts don't have an insertion method).
(List comprehension is faster here, but will be a longer statement.)