title: Specify base package in protobuf compilation in golang
body: <p>I've got golang package <code>github.com/user/protoapp</code>, in this package I have folder <code>proto</code> containing protobuf files.</p>
  
  <pre><code>github.com/user/protoapp
  |-proto
  |-proto/app1
  |-proto/app2
  </code></pre>
  
  <p>proto files in <code>app1</code> and <code>app2</code> have corresponing packages <code>app1</code> and <code>app</code>;</p>
  
  <p>Proto file from <code>proto/app1</code> is importing file from <code>proto/app2</code> like <code>import "app2/messages.proto";</code> after compillation in <code>app1.pb.go</code> it becomes <code>import app2</code> and <code>protoapp</code> fails to compile. How do I make imports in <code>*.pb.go</code> files become <code>import "github.com/user/protoapp/proto/app2"</code> rather than <code>import "app2"</code>?</p>