Speed up `ChunkedBitIter`

The current implementation is slow because it does an operation for
every bit in the set, even zero bits. So if you have a large bitset with
many zero bits (which is common) it's very slow.

This commit improves the iterator to skip over `Zeros` chunks in a
single step, and uses the fast `BitIter` for `Mixed` chunks. It also
removes the existing `fold` implementation, which was only there because
the old iterator was slow.

0 files changed, 0 insertions, 0 deletions