Importing a fully qualified enum doesn't work

[davidlar]

Example:

enum_to_import.proto:

package resources.generated.nested;

enum AnEnumToImport {
  KEYBOARD = 1;
  MOUSE = 2;
}

import_enum.proto:

package resources.generated;

import "enum_to_import.proto";

message AnImportEnumMessage {
  required resources.generated.nested.AnEnumToImport to_import = 1;
}

doesn't compile.

[davidlar]

Fix added to pull request #107