pgbitmap 0.9.3

Announcing the latest Beta release of pgbitmap, available from [pgxn](https://pgxn.org/dist/pgbitmap/)
and [github](https://github.com/marcmunro/pgbitmap).

pgbitmap provides a bitmap datatype for Postgres with a full set of functions, operators and aggregates.

This release fixes a number of issues with empty bitmaps and is considered a production release candidate. Any and all feedback is welcomed.

A bitmap is an array of bits, indexed by an integer. Bitmaps provide an efficient means to implement sets of integers. pgbitmap provides functions and operators for:

- creating new bitmaps;
- adding elements to bitmaps;
- removing elements from bitmaps;
- testing for inclusion of elements in bitmaps;
- finding the minimum and maximum bits in bitmaps;
- unioning bitmaps together (set union/logical or);
- intersecting bitmaps (set intersection/logical and);
- subtracting one bitmap from another;
- converting bitmaps to and from textual representations;
- converting bitmaps to and from arrays;
- aggregating bits and bitmaps into bitmaps.

It differs from the standard Postgres bitstring in that it isn't based around bit zero (bitmap(1000000) does not contain 1,000,000 zeroes followed by a 1) and it has more functionality.

It was developed primarily in order to efficiently manage sets of privileges for Virtual Private Database implementations.

Full documentation is available [here](https://marcmunro.github.io/pgbitmap/docs/html/index.html)