session: switched to uint64_t instead of size_t. Added offset/size read/write parameters.
session: added GetGroup(), store groups in local session. Added chunked read and streaming read interface, which streams data into http pipe
node: extended default logger format
node: increase default number of io/net node's threads. Fixed blackhole log formatter.
node: fixed node creation check, return error if not could not be created
Merge pull request #11 from bioothod/v2.26

2.26: new API and bugfixes