Add a test which iterates over all (or at least some) tables and verifies that the characters have norm 1?

[fingolfin]

@SoongNoonien has some concern that this may be too slow if we do it for all. So this raises a few new questions

• how long does it take to just load all tables?
• how long does it take to compute all norms for some specific tables (maybe a small one vs. a "big" one)
• how long does it really take to compute all norms on all tables?

Besides timings it would also be very interesting to know more about the memory usage (e.g. how many allocations and how many MB/GB/... of RAM are used to e.g. load a single specific table; load all tables; etc.)

When we have some numbers, we can then also use this as an opportunity to look into tuning the code...

[fingolfin]

Now that we already perform tests for all tables in test/runtests.jl:105 we could start looking into doing this as well?