Fix problems with !def

[MysteryBlokHed]

For some reason, having two or more !def lines causes all but the first not to work. The !def lines are excluded from the output, but the text is not replaced. For example, this code:

!def t1 test1
!def t2 test2

func main
    say t1
    say t2
end

Compiles to:

say test1
say t2