Support bracket-less array syntax for "args"

[hmans]

You can set array attributes like this:

position="[0, 5, 10]"

And you may omit the brackets:

position="0, 5, 10"

This is currently not allowed for the args attribute, which you always have to set like this:

args="[1, 2, 3]"

Let's make it so we can also do this:

args="1, 2, 3"