[Rpm-maint] Enforce install/erase order without adding a Requires:

[FlorianFesti]

Hi!

There have been various issues with packages that demand a special order 
of installation but do not want to Require the package to be installed 
first. So a tag that is like Requires: during ordering but ignored 
otherwise is needed.

Panu had a look into the problem yesterday and it turned out this can be 
done by simply adding a new tag triple and very few additional lines of 
code. But it also turned out that's really hard to come up with a good 
name for it. After banging our heads against the wall for the morning we 
settled on "OrderWithRequires:" It is not really beautiful but here are 
the reasons why we preferred it over two dozen other options:

* It contains "Requires" which make clear that it is handled exactly 
like normal Requires during ordering.
* We considered using "Sort" instead of "Order" as its less ambiguous 
but "order" is already part of the rpm nomenclature (--noorder).
* It does not contain "before" or "after" which get wrong when it comes 
to ordering erases.
* OrderWithRequires(pre) is supported and looks familiar.
* It offers adding OrderWithRequiredBy later for adding a reverse relation.
* It's long and descriptive. As it is going to be rarely used typing 
effort is not an argument.

Nevertheless we still have the feeling there might be better names. 
Suggestions are welcome!

Florian