[Mac] New zenmap_auth_wrapper in Objective-C

[ghost]

The Objective-C zenmap_auth.m file replaces zenmap_auth.c.
Its main purpose is to call applescript scripts to launch Zenmap with a "helper tool" (an authorisation wrapper), that will launch Zenmap with/without administrator privileges.

Waiting for your comments!
Cheers,
VincentD

[dmiller-nmap]

This works like a charm, thanks! I think that instead of changing $CC to clang directly, we should change gcc to clang at the top of the script where CC is set. Nothing else in the script uses CC, so there's no reason to set it to something that won't be used.

[ghost]

The pleasure is mine. You are right I am going to commit the corresponding changes right away. Thanks for your time and review!

[ghost]

Since I deleted the branch by mistake, I just opened a new PR: #456, which closes this one.