EventSeeder: use vector of pairs to fix order of seeding processors

[andresailer]

The loop over the map is not guaranteed to be constant across time or space so event seeds were not reproducible, because the order of the pointer to the processors depends on the memory.

Now use a vector with fixed order from processors calling to register themselves, which is constant.

BEGINRELEASENOTES

• EventSeeder: make event seed truly constant in space and time

ENDRELEASENOTES

[gaede]

@andresailer would it not have been easier to replace std::map<Processor*, unsigned int> with std::map<std::string, unsigned int> and then use Processor::name() as key ?

[andresailer]

Then you cannot take out processors after the one you are interested in.

[gaede]

Ok, fair enough.