Ordering of PEnum items

[aothms]

Note that this is a minor issue that only affects documentation.

At some point the decision was made to order PEnum items alphabetically with notset et al. last.

It was brought to our attention that manual ordering of penum items was explicitly implemented in IfcDoc.

At least in one case there is a meaningful discrepancy

PEnum_BackInletPatternType

Where the original was:

1/2/3/4/12/13 ...

One now we have (per character lexicographically)

1/12/123/2 ...

This can be solved by either:

• bring back the explicit ordering by means of the UML tags
• sort more intelligently (i.e Natural Ordering https://en.wikipedia.org/wiki/Natural_sort_order) to at least solve the particular issue where this was observed.