Bored Now: added XML comments
Micro optimisation: optimized Buffer<T>.ToList() for small, single-page results

- Most short range queries, like FirstOrDefault() or SingleOrDefault() only have a single result that can be added quickly without needing a tmp array
System: reduced the max window size of Fdb.System.EstimateCountAsync

- When counting in subspace with very large values, a window size of 65536 need to traverse a LOT of data (multiple Gigs)
- Smaller initial window size to help count in almost empty subspaces that are right before a huge subspace with very large keys
- This is still not ideal. Counting ranges with large keys and/or values is currently sub-optimal and may trigger a lot of future_version errors
Compressed Bitmap Indexes: [Work in Progress] very rough first prototype of compressed bitmaps encoding and decoding

- Uses a variant of Word Aligned Hybrid coding with 32 bits words and 31bits literals.
- Supports APPEND, SET, CLEAR, AND, OR and XOR on compressed bitmaps without needing to uncompress them
- Compressed words are in stored in little endian (host order) to simplify things a lot.
- Don't use this yet, it's still full of bugs !
Fixed test regression: KeyComparer of an index merge expression can be null