Release 6.1.0 (NNCP)

Optimization: most commands do not keep opened file descriptors now. Previously you can exceed maximal number of opened files if you have got many packets in the spool directory.
Optimization: do not close file descriptor of the file we download online. Previously each chunk lead to expensive open/close calls.
Online downloaded files are saved with .nock (non-checksummed) suffix, waiting either for nncp-check, or online daemons to perform integrity check.
Optimization: files, that are not resumed, are checksummed immediately during the online download, skipping .nock-intermediate step.
Ability to store encrypted packet’s header in .hdr file, close to the packet itself. That can greatly increase performance of packets listing on filesystems with big block’s size.