This function can be used for any protobuf message which contains required,
repeated and even nested messages fields.

The functions doesn't support yet:
1) Optional fields (skipped)
2) Fields types: PROTOBUF_C_TYPE_FLOAT, PROTOBUF_C_TYPE_DOUBLE,
PROTOBUF_C_TYPE_BOOL, PROTOBUF_C_TYPE_ENUM, PROTOBUF_C_TYPE_BYTES.
These are show as unknown objects.

IOW, it supports only existent proto files.
Inspired-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Stanislav Kinsbursky <skinsbursky@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>