Visible in Mask on Script

[FrostKiwi]

There is a bug in corona, making Materials invisble on certain render elements, which screwed me over. It happens by corona unchecking "Visible in mask" Checkbox, when jumping between the daily builds and the official build.
I was promised a script that would check that back automatically, for my scene with 200+ materials. Since there is no such script in the Goodies section, I found it via google custom search in the resolved bugs forum, originally submitted by mirokurcik. So I reuploaded here, should there be a soul of similar fate searching for an answer.

tl:dr
Script checks "Visible in Masks" checkbox for every material in the scene.