disk space. added tagdb file cache for better performance,
less disk accesses. will help reduce disk load.
put file cache sizes in master controls and if they change
then update the cache size dynamically.
if empty query or n<=0 and &stream=1 then fix bug
that was not sending back the reply properly.
basically, disable streaming if msg40 would not block.
upped MAX_SHARDS from 128 to 1024. should not take up
any more mem really or slow things down.
