log: made eblob_dump_id_len() and friends thread-safe by using per-thread allocated temporal buffers
iterate: updated iterators - exported new iterator similar to what is present in C code, get rid of old iterator class
example: get rid of unused regex iterator, it used old iterator code, which did not take into account ext headers for example
example/embed: added boost::program_options deps, added old elliptics embedded structure checks
eblob: added plain_write() method, which is a wrapper on top of eblob_plain_write()