readme: fixed .rst formatting
binlog: fixed description of binlog.c
data-sort: removed unused locking parts
hash: removed debug iterators
binlog: check that fd is not changed even without binlog
data-sort: sleep between defrag iterations

Just in case some external program cached fds provided by libeblob we
add some grace period after which we assume it's safe to close old data
and index fds.
data-sort: do not check return value of pthread_mutex_unlock

Requested by: zbr@
data-sort: do not use abort in library
data-sort: use grace period only if binlog requested
data-sort: added comment about base removal
ci: reopen blob after 20k iterations