Use ncompress for LZW decompression

[valgur]

Hi! This PR replaces unlzw3 and unlzw with ncompress for LZW decompression. Support for LZW compression and decompression was a bit lacking in Python, so I created a new ncompress library to address that and add .Z output support to hatanaka. I thought you might find its decompression functionality useful as well. Like unlzw, it is 40x faster than unlzw3, but the former currently has a memory leak issue. It is based on the de-facto standard (N)compress utility with only minimal changes to port its interface to C++ and should be as robust as it gets as a result.