v0.6.1

Changelog

9abaeeb fix: binary method lookup works for struct field pointer receiver
03596da fix: correct automatic type conversion for untyped constants
35e645c fix: correct handling of types alias of interfaces
effd64c fix: handle forward declaration of alias type
0f46cd5 fix: handle type declaration inside function
8a88a1a fix: range over string iterates on runes instead of bytes
030dd3c fix: support variadic parameters on methods
8db7a81 interp: don't panic for undefined types