Support for multiple arguments per RFC per user

[brendt]

Depending on a user's reputation, they should be able to make multiple arguments per RFC. Every user starts with 1 argument though.

• Show argument counter when a user has more than one argument available
• Notify users somehow when they've passed a reputation threshold and have multiple arguments
• Creating additional arguments is done in the same way: by pressing the vote bar and writing an argument. There should be an explanatory text to let users know they are making another argument

[brendt]

I'm actually not sure whether it's worth investing time in this one:

• Allowing multiple arguments for the same RFC requires a major UI refactor
• I don't think many people would want to make several arguments

Maybe someone has good input here. Feel free to share your thoughts.

[brendt]

Not doing it for now