Change: remove warning in cheat window and reduce it to a note (#8538)

Although meant as a funny joke towards the player, our social
standards have changed since 2004, and such "jokes" are no
longer acceptable by the community as a whole.

The only value of the message is that people are informed the
information is stored in the savegame. This is mostly useful for
us, developers, as some of those cheats can have side-effects
which people report.

While at it, styled the GUI a bit better, as the way the text
was presented was odd.