concat vex function

Contexts: chop , cop , displace , fog , image3d , light , photon , pop , shadow , sop , surface

Tags: string

Concatenate all the strings specified to form a single string.

1. string concat(string s1, string s2)

Concatenate all the strings specified to form a single string. This is equivalent (but slightly more efficient when there are more than 2 strings) to adding all the strings together.