Parameterize uri resolution and parsing of options, use package:path

lib/protobuf_field.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of protoc;
 
 class ProtobufField {
   static final RegExp HEX_LITERAL_REGEX =
       new RegExp(r'^0x[0-9a-f]+$', multiLine: false, caseSensitive: false);
   static final RegExp INTEGER_LITERAL_REGEX = new RegExp(r'^[+-]?[0-9]+$');
@@ skipping 354 matching lines @@
 
     // For groups, use capitalization of 'typeName' rather than 'name'.
     if (codedStreamType == 'Group') {
       String name = _field.typeName;
       int index = name.lastIndexOf('.');
       if (index != -1) {
         name = name.substring(index + 1);
       }
       return underscoresToCamelCase(name);
     }
-    var name = context.options.fieldNameOption(fqname);
-    return (name != null) ? name : underscoresToCamelCase(_field.name);
+    var name = context.options.fieldNameOverrides[fqname];
+    return name != null ? name : underscoresToCamelCase(_field.name);
   }
 
   int get wireType {
     switch (_field.type) {
       case FieldDescriptorProto_Type.TYPE_INT32:
       case FieldDescriptorProto_Type.TYPE_INT64:
       case FieldDescriptorProto_Type.TYPE_UINT32:
       case FieldDescriptorProto_Type.TYPE_UINT64:
       case FieldDescriptorProto_Type.TYPE_SINT32:
       case FieldDescriptorProto_Type.TYPE_SINT64:
@@ skipping 10 matching lines @@
         return 2; // Length-delimited
       case FieldDescriptorProto_Type.TYPE_GROUP:
         return 3; // Start group
       case FieldDescriptorProto_Type.TYPE_FLOAT:
       case FieldDescriptorProto_Type.TYPE_FIXED32:
       case FieldDescriptorProto_Type.TYPE_SFIXED32:
         return 5; // 32-bit
     }
   }
 }