- compression: now use "fastest" compression mode and more memory unless
in FINAL build. this greatly speeds up archive generation at expense of
1.5% size increase (fine during development). done because profiling
shows ZLib accounts for 78% of CPU; practically nothing else shows up,
which shows effectiveness of compressing in parallel with reading from
disk.
- file_cache: documented; fixed several potential issues with exact_buf
when invalidating files.
This was SVN commit r3586.