Decode is missing nil handling / common basic coercions about go-mruby HOT 1 OPEN

Here is a first (fairly arbitrary) stab aiming to keep it simple.

Horizontal types are ruby
Vertical types are golang

Array / map conversions will follow key / value type conversion rules for each element. (e.g. map[string]float would follow string conversion rules for keys and float conversion rules for values).

Structs, user types & enums are not covered due to potential complexity of mapping.

I'm not sure if float -> int should be allowed due to precision loss. Dynamic languages typically allow this though.

It's also quite strict and does not allow (for instance) Fixnum -> bool conversion.

Due to the breadth of work implementing this will require I will await feedback before proceeding.

from go-mruby.