Var decl refactor

We need to include the ID of a variable in the `vdecl` type to do anything useful in the SAST.
I also think it'll be simple to work with it if we have the value in an `expr option`.

Thoughts? @bfish713

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Also refactored `println` to take an arbitrary number of expressions.
this was unused because it was formally used in microc for global variables.