Update trellis quantization to support progressive coding mode

Trellis quantization is modified:
- to work on the configurable spectral range Ss to Se
- to optionally optimize runs of EOBs
- to optionally split optimization between 2 spectral ranges
In trellis quantization passes Huffman table code optimization is
modified such as to generable a valid code length for each possible
symbol by resetting frequency counters to 1 instead of 0
Add option to perform multiple trellis quantization iterations

Multiple trellis iterations may improve coding performance as Huffman
tables are updated with each iteration. In practice the benefit appears
to be very minimal