Ofscreen lines

The animation of the simple_menu used in the main menu had the issue that there is a black line visible at the top. This is due the gfx_puts method ignoring lines, where the top pixel of the string is above the top of the screen. As gfx_puts uses gfx_setpixel which in turn ignores pixels outside of the screen, I removed the check in gfx_puts.

I also removed the ranges from the documentation of the individual python functions and added a general documentation about the screen and it's ranges.

Related: https://git.card10.badge.events.ccc.de/card10/firmware/issues/178