compiler: save both VM and smartcontract types

VM types are used in debugger, while smartcontract ones are used in
manifest. We can't save only one of them, because conversion in either
side is lossy:
1. VM has `Array` and `Struct` but smartcontract only has `Array`.
2. Smartcontract has `Hash160` etc, which are all `ByteString` or
`Buffer` in VM.

And to spice things a bit more, return type in debugger can be `Void`,
which corresponds to no real stackitem type (as it must exist).

pkg/compiler/codegen.go

@@ -877,7 +877,8 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 				tv := c.typeAndValueOf(n.Args[0])
 				params := make([]string, 0, len(n.Args[1:]))
 				for _, p := range n.Args[1:] {
-					params = append(params, c.scTypeFromExpr(p))
+					st, _ := c.scAndVMTypeFromExpr(p)
+					params = append(params, st.String())
 				}
 				// Sometimes event name is stored in a var.
 				// Skip in this case.