Other HDS implementations
Collect “utils” module

* CounterWriter is now a wrapper around another stream
* Drop abort event flag from streamcopy()
* Add utils.fastforward() in preference to the “nullwriter” object
Split off “flvlib” module

* Add read_packet_header(), write_file_header(), write_scriptdata()
Add parsing of audio and video FLV tags
Specifically avoid repeating the AAC and AVC sequence header tags

Assume that the header tags only occur at the start of each fragment, to
avoid slowing the code down.