Build output string in component_table_entry() as the similar strings
in generate_bom(). Repeating a couple of minor if-expressions is small
cost to obtain a more compact and readable main expression.
Make a list from the group iterator for reusage in sum expressions
and to pick first group entry. The expected group sizes are very small,
so performance loss by creating a temporary list should be neglectable.
Alternativly, itertools.tee(group, 3) could be called to triplicate
the iterator, but it was not chosen for readability reasons.
- Use one common entry loop to consume iterator only once.
- Use same key function for sort() and groupby(),
except replace None with empty string when sorting.
- Use the actual BOM as first parameter instead of the whole harness.
- Use a whole AdditionalComponent as second parameter instead of each
attribute separately.
