Allow None and Some to be inline parameters

[nicolasstucki]

Allow inline parameters to have type Option[T] for some inlinable T. It will allow know the value of a statically known Option[T] at macro expansion type (without TASTy reflection).

inline def foo(inline opt: Option[Int]): Int = ~impl(opt)
def impl(opt: Option[Int]): Expr[Int] = opt.getOrElse(-1).toExpr

foo(None) // ok
foo(Some(1)) // ok
foo(new Some(1)) // ok
foo(opt) // error
foo(Some(n)) // error

This is quite useful in combination with valueOpt[T].

This is a first step into knowing statically structured values. It will be extended in the future for tuples, lists and maybe a restricted subset of case classes.

[nicolasstucki]

Rebased