Newlines are removed from botcmd args

[zaughon]

Describe the bug
The fix to #1307 means that all newlines are split and eventually replaced with spaces:
https://github.com/errbotio/errbot/blob/master/errbot/core.py#L340

In general, i think it's best if the args stay as unmodified as possible, and then you can manipulate it with args.replace("\n", " ") yourself if you want something specific in certain situations.
Currently i'm looking into making something that may take large blobs of text and store that in a DB, and need to pull it out later and display it. It gets very messy when all newlines are removed though.

To Reproduce

    @botcmd
    def hello(self, msg, args):
        return 'Hello! You said: ' + args

    @botcmd
    def repr(self, msg, args):
        return 'Hello! You said: ' + repr(args)

$ pip3 install errbot
$ errbot --init
$ errbot
...
# Enable multiline mode with !ml if it isn't already
>>> !ml
>>> !hello
[.] Line 1
[.] Line 2
[.]
Hello! You said: Line 1 Line 2

>>> !repr
[.] Line 1
[.] Line 2
[.]
Hello! You said: 'Line 1 Line 2'

Expected behavior
Linebreaks between "Line 1" and "Line 2" are preserved: Line 1\nLine 2

Screenshots
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Environment (please complete the following information):

• Errbot version: 6.2.0
• OS version: Arch
• Python version: 3.13.2
• Using a virtual environment: yes
• Using Docker: no

Additional context
Add any other context about the problem here.