Allow multiple commands per message

[Sinthorion]

Sometimes a user writes multiple commands as one command per line in a single message, expecting the bot to understand it as separate commands. Maybe we could split the input text on all newlines and treat each line as its own command.

Example:

<User>:
.iam Merchants
.iam Español
<Ducky Mc Duckerson>:
Cannot find any role by the name 'Merchants
.iam Español'

Issues:

• Potential performance loss, because split is a more demanding operation than checking for a single prefix
  => Split should only be applied after a prefix was found at the start of the message
• Reactions to the message (such as the checkmark for success) are ambiguous