Simple BitSet

A dead simple bitset. Not generic at all, it only stores u8s and nothing else. For its underlying storage it uses a [u64; 4]

Attempts to match the interface of std::collections::HashSet with some exceptions.

HashSet methods not implemented for simple BitSet

• get_or_insert_with: The sepc of this is a headache. I can try to add this if someone requests it.
• entry: Unneeded becuase u8 is Copy.
• hasher: Nonsensical since this is not a hash set.
• reserve: Nonsensical since the bitset has a fixed size of 256.
• shrink_to: Nonsensical since the bitset has a fixed size of 256.
• shrink_to_fit: Nonsensical since the bitset has a fixed size of 256.
• try_reserve: Nonsensical since the bitset has a fixed size of 256.
• with_capacity: Nonsensical since the bitset has a fixed size of 256.
• with_hasher: Nonsensical since this is not a hash set.
• with_capacity_and_hasher: See above.