Initial commit

Original fcrackzip source downloaded from:

    http://oldhome.schmorp.de/marc/fcrackzip.html
Add missing types.
Fix a printf format specifier.
Use fork/exec rather than system()

- better handling of weird characters in passwords.
Update configure script

- support clang
- look for system unzip by full path
Cleanup some autoscan warnings.
README updates.
config.h cleanup
Support clang directly via configure script.