support void type of function

[YSawc]

modify support void type of function. I noticed that only reference assignment function that does not returns value is not supported yet.

[dalance]

Thank you for your contribution.
I think there is another solution to support void function.

// void return type support
function Func () -> void {
}

// omittable return type
function Func () {
}

How do you think?

[YSawc]

It sounds good! May i change logic to apply your suggestion?

[YSawc]

@dalance
194a685
I changed to apply omit return type. Please confirm changed logic.

[dalance]

Looks good!
I've added a comment about alignment of emitter.
Could you check it?

[YSawc]

Thanks your feedback! I applied each suggestions.

[dalance]

Thanks!!
I'll merge this PR.