More methods?

[bovee]

There are a number of methods in the standard library bit vector that it might be nice to support here too such as:

• set_all, clear, negate: set all bits
• all, none, any: check all bits

It would be nice to also have some basic information to determine how "full" a bit array is, especially for Bloom filters, etc:

• count: count the number of set bits. Note that this would be equivalent to something like bv.rank(bv.len()) so implementing that may be preferable (see issue Add more functionality to support succinct data structures #2 for tracking rank/select implementation).

Open question if all of these functions should take no arguments or if they should take something that implements RangeArgument to allow finer granularity.