show[Raw] and show[Code]

review @densh
Needs to change:
```
    case t: Decl.Val       => s(t.mods, "val ", r(t.pats, ", "), t.decltpe)
    case t: Decl.Var       => s(t.mods, "var ", r(t.pats, ", "), t.decltpe)
```
To:
```
    case t: Decl.Val       => s(t.mods, "val ", r(t.pats, ", "), ": ", t.decltpe)
    case t: Decl.Var       => s(t.mods, "var ", r(t.pats, ", "), ": ", t.decltpe)
```