Windows binaries: working with compressed files

[frederic-mahe]

@GuilhemSempere reported that the vsearch Windows binaries do not accept compressed files by default and require additional dlls.

Indeed, on a fresh and up-to-date Windows 10 install, trying to read a compressed gzip or bzip2 fasta file with any vsearch release (v2.3.4 to present) returns an error message:

Fatal error: Files compressed with gzip are not supported

or

Fatal error: Files compressed with bzip2 are not supported

Installing git (x64), searching C:\Program Files\Git for zlib1.dll, and copying the library to C:\Windows\System32 allows to process gzip'ed files.

However, downloading libbz2.dll (x64 or x86) and putting libbz2.dll either in C:\Windows\System32 or C:\Windows\SysWOW64 does not work. When putting libbz2.dll (x64) in C:\Windows\System32, vsearch does not complain but the output file is empty (silent failure). All other combinations trigger vsearch's bzip2 error message.

Note: renaming libbz2.dll into bz2.dll and running vsearch also triggers an error message:

Fatal error: Files compressed with bzip2 are not supported

The README file should be modified to reflect that name change (libbz2.dll rather than bz2.dll).