v2.24.13.19
Added little optimization for cache

Write with zero offset case
Merge pull request #196 from euroelessar/master

Added little optimization for cache
Do not mess with command flags, instead unlock/lock key. Otherwise final ack will be sent without lock and will be processed in non-blocking pool in parallel with blocking replies, which will force client to drop some of its replies (which have not been yet processed).
Fixed invalid error for read in case if there is no state

dnet_mix_states sometimes returnes 0 as result, which is invalid
Added reconnection logic debug

Conflicts:
	library/dnet_common.c
v2.24.13.20
Fixed using of mix_states for DNET_CFG_MIX_STATES
v2.24.13.21
Moved dnet_time_before/after into public header.
v2.24.13.22
Use dnet_time structure in dnet_time_before/after functions
Use 0xHEX string instead of just HEX
Use pointer logic in indexes. Only drop lock (and do not unlock at the end of dnet_process_cmd_raw()) if we are not going to send ack right now.
v2.24.13.23
Fixed groups mix in case of key generated from id
Added session::update_indexes method
v2.24.13.24
Added dnet_indexes_reply for internal commands
v2.24.13.25