Experimental ZX0 support

[fadden]

As part of fadden/nulib2#16, ZX0 compression for NuFX archives has been added to CiderPress II v1.0.8-dev1. The current implementation is about 300x slower than any other supported algorithm when compressing data, so I don't see this being something most people will have a use for.

Files are decompressed as they would for any other format. For compression, the current implementation uses a special command-line option that is used to kluge experimental features in. It allows you to override the default NuFX compression type (LZW/2), by number. The numbers are:

1. SQueeze (RLE+Huffman commonly used in Binary ][)
2. LZW/1
3. LZW/2
4. LZC-12
5. LZC-16
6. Deflate
7. Bzip2 (not supported)
8. ZX0

To specify ZX0 compression, you would add --set-int=nufx-comp-alg:8 when adding files.

For example, to copy all files from a disk image to a ShrinkIt archive with ZX0 compression, you could use:

% cp2 cfa test.shk
% cp2 copy --set-int=nufx-comp-alg:8 The\ Print\ Shop\ Companion\ v1.2\ side\ B.woz test.shk

Then, to admire the results:

% cp2 v --wide test.shk
File: test.shk
Typ Aux  HTyp Crea Access Created         Modified        D-Length   D-Size D-Fmt   R-Length   R-Size R-Fmt   Name
--- ---- ---- ---- ------ --------------- --------------- -------- -------- ------- -------- -------- ------- ----
[...]
BIN 7800 0000 0000 r      [No Date]       [No Date]            576      161 ZX0            0        0 (n/a)   AE
[...]

Files can be viewed and extracted with the GUI application, but there's currently no way to override the compression type there.