Labels are marked undefined unless defined before goto

[mika76]

I see in #16 there was a fix for labels, but it seems to work only if the label is defined before the goto, if for eg you want to jump out of a couple of loops to a label below it is still marked as undefined (but works fine in pico-8)

[japhib]

That makes sense, I think when checking gotos it just naively looks for labels defined before it only. This should probably be a quick fix.

[japhib]

Fix released just now with 0.4.10