Unary minus?

[tareksander]

I expected that something like *create variable -2 would create a variable with the value -2, instead it gives the following error: "Invalid create instruction, too many values: variable -2". Doesn't work even if the -2 is inside parentheses.

I could just write 0-2, but that's very unintuitive.

[rocky2049]

I just submitted a pull request that could add support for this
#149