Provide option to use proto files instead of reflection

[rainerschoe]

Is your feature request related to a problem? Please describe. server might not support reflection

Describe the solution you'd like give optional proto file path as CLI argument, if given, reflection is not used

Describe alternatives you've considered none

Describe why you think this feature is useful for gWhisper users

• sometimes servers do not have reflection enabled.
• Users will have increased performance when using local proto files instead reflection over slow network.