Benchmark panics

[jpochyla]

Running benchmarks with:

cargo bench --features simple_iter

fails with the following error:

Benchmarking hi_sparse_bitset insert: Warming up for 3.0000 s
thread 'main' panicked at .../hi_sparse_bitset/src/raw.rs:141:9:
2080768 index out of range!

[tower120]

I'll take a look at it. Sorry for delay.

[tower120]

The reason for that, is that max range for 128bit container is actually 127^3, not 128^3. At each level one block occupied for "empty" pointers (for performance reasons - to avoid branching).

In SmallBitSet that additional is actually not allocated, but max_capacity() calculated the same way as in BitSet - for code simplicity.

Fix on dev branch now

[tower120]

On main branch and in release now.