The generated encode functions that have a naked return (simply "return") where the function returns an error type all have the "err" variable declared as a named return (as it is here in the func "appendraw"). But this is the only place where the "return" is followed by a " err"; this is unnecessary because the return value is named in the function signature.

* make AppendExtension output same as WriteExtension

…her clients (#215)

Allow non-overflowing uints to be read using ReadInt and vice-versa

Before this change Unmarshal of a Marshaled empty Raw would yield
a byte slice with a Nil marker in it. This change makes Unmarshal
consume the marker and return an empty slice.

Unsafe pointer arithmetic is not supported under GopherJS,
and currently fails silently.

Add the `purego` tag, standardized as part of golang/go#23172,
in addition to the `appengine` tag kept for backwards compatibility.

Fixes a problem that `go vet` complains about:
```
should omit 2nd value from range; this loop is equivalent to `for key := range ...`
```

add field compatibility with vmihailenco/msgpack

An empty map in the data should result in an empty map in Go. It's a
small performance loss in the rare cases where people have empty maps in
their data and use structs with maps that haven't been initialized yet.
But for correctness it's better and it allows people to distinguish
between no map in the data or an empty map.

Fixes #219

The inliner must perform inlining in a deterministic
order in order for the generated code to be
deterministic.

This patch uses a "bottom-up" inlining heuristic:
the least complex types are inlined first, followed
by more complex types (if the fixed inlining "budget"
still allows it.)

Fixes #239