Multiple variable gcd patch (Attempt #2)

[Reptorian1125]

Again, sorry if I screwed up anything by using -f on the last time. Struggling with git as this is still new to me. Anyways, the changes to gcd() allows for these examples:

C:\Windows\System32>gmic echo {gcd(30,16,20)}
[gmic]./ Start G'MIC interpreter (v.3.3.3).
2
[gmic]./ End G'MIC interpreter.

C:\Windows\System32>gmic echo {gcd([30,16],20)}
[gmic]./ Start G'MIC interpreter (v.3.3.3).
2
[gmic]./ End G'MIC interpreter.

C:\Windows\System32>gmic echo {gcd([30,16,20])}
[gmic]./ Start G'MIC interpreter (v.3.3.3).
2
[gmic]./ End G'MIC interpreter.

C:\Windows\System32>gmic echo {gcd(30,[16,20])}
[gmic]./ Start G'MIC interpreter (v.3.3.3).
2
[gmic]./ End G'MIC interpreter.

C:\Windows\System32>gmic echo {gcd(320,240)}
[gmic]./ Start G'MIC interpreter (v.3.3.3).
80
[gmic]./ End G'MIC interpreter.

C:\Windows\System32>gmic echo {gcd(320,240,25)}
[gmic]./ Start G'MIC interpreter (v.3.3.3).
5
[gmic]./ End G'MIC interpreter.

C:\Windows\System32>gmic echo {gcd([1520,10000],[500,250])}
[gmic]./ Start G'MIC interpreter (v.3.3.3).
10
[gmic]./ End G'MIC interpreter.

[Reptorian1125]

This pull request is closed as not needed any more.