Introduces Equil, a thin storage class for 'EQUIL' derived information,
accessible through EclipseState.
Previously this was handled through "raw" deck access, provided by
EquilWrapper. The interface for Equil has been derived from the
EquilWrapper, but they're to be seen as different entities altogether.
More importantly, Equil is owned by EclipseState, not some stand-alone
Deck reading unit.
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.
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.
