Use seg_object to store immediates or pointers.
Adapt to seg_object API changes.
Update seg_object tests.
Update unit tests to use the new API.
Integer immediate bugfixes.
seg_stringlike_contents needs a seg_object*.
Test immediate symbols.
Test with non-immediate symbols.
Handle immediates in the symboltable.
Stub out the storage probe method.
Rename seg_class to seg_object_class.
Bootstrapping and slotted storage, part I.