Since the Deck* family of classes have changed their interfaces to no
longer use shared_ptr, a lot of code broke. This patch fixes all
problems in tests, other signatures and accesses to now use the new Deck
interfaces.
The deck no longer exposes shared_ptrs, but uses automatically managed
memory, meaning ownership of DeckKeywords are now obvious and clear.
shared_ptr in the interface has been replaced by references.
This refactoring reflects the ownership semantics of Deck* classes -
Section and Section-derived classes no longer claim ownership over
partial decks, but rather provide a -view- into an already
established Deck.
The Deck class itself is now unique in the sense that it is the only
supporter of write operations, meaning a DeckView derived instance can
never modify the deck it's viewing.
Every header is self-contained and includes only what it must to
function, relying on users include what they need in source files,
adopting a pay-what-you-use model (in particular for internal
dependencies).
This is an effort to improve build performance. Several includes
scattered across the project are either unused or partially used (i.e.
just used to import a type name, not depending on the actual contents of
the header file).
Replaces a lot of these includes with forward declarations.
