Add an config option to chose a different console error color

[Ekopalypse]

closes #212

[alankilborn]

This is fine, but I thought the solution you provided HERE was elegant.

[Ekopalypse]

You're right, but because it was labeled as an enhancement, I did it.
I also have no problem with the PR not being merged if the startup.py solution is accepted as a solution.

[chcg]

At that time I was not aware that the colour could be changed by pythonscript call. As it is already implemented I'm fine with this solution which is probably easier to handle by new users.