Parser should accept Lua paren-less function calls with a single string or table literal
Lua allows parentheses to be omitted from a function call if there is exactly one argument and the argument is a string or table literal. picotool does not yet support this case. PICO-8 supports it and offers a one-token discount compared to a similar call with parentheses.

```
function foo(arg) ... end

foo"single string argument"
foo{a=1, b=2, c=3}
```

I'm not sure how important this is to support, but I'm creating an issue for it just so we can track it. Upvotes and feedback welcome.