Replace custom unzip functions with standard ones

unz[SG]etCurrentFileInfoPosition() isn't needed anymore,
because newer minizip versions have unz[SG]etOffset() for
that purpose.
Merge branch 'update-zip' of https://github.com/DanielGibson/dhewm3
framework -- add console command "dumpCmds" which generates the
markdown-file "commands.md" in the execution directory"