base: Rewrite the CircleBuf to fix bugs and add serialization

base: Rewrite the CircleBuf to fix bugs and add serialization

The CircleBuf class has at least one bug causing it to overwrite the
wrong elements when wrapping. The current code has a lot of unused
functionality and duplicated code. This changeset replaces the old
implementation with a new version that supports serialization and
arbitrary types in the buffer (not just char).