Add missing 'inline'.
filesystem/v3/path.hpp -> filesystem/path.hpp
Increase the size of integral types representing the sizes of key
type, mapped type, and node size, to accommodate use cases where the
key and/or mapped type is very large, or where there are a large number
of nodes.
Warning reduction via static_cast<>.
Save size of key and/or mapped type into headers, instead of -1.
Throw when the key or mapped size of an opened btree does match
expectations.
Add limited transaction semantics to the open operation.  This means
that when a user tries to open a btree that throws because it is not a
btree or is otherwise malformed, the user can retry without having to
manually close the btree before attempting another open.