...since that is what it meant to be.
To allow this chance, I've now added a default ctor to lib::Literal,
defaulting to the Symbol::EMPTY (the interned empty string)
...under the assumption that the content is normalised,
which means
- leading NULL is changed to Symbol::EMPTY
- missing elements in the middle are marked as "*"
- trailing NULL in extension storage is handled by adjusting nominal extension size
after various fruitless attempts to rely somehow on the array variant of unique_ptr,
I ended up with a hand coded version of an heap allocated array, managed automatically
