pbsplash multi-line fixes

This fixes \n in pbsplash, we need a printf in the show_splash functions to actually convert the \n to a literal newline.

This also fixes a bug reported by @z3ntu where when a long piece of text with no spaces in (e.g. a URL, or a URL preceded by the characters active\n, heh) is longer than the width of the display. The line splitting code would get stuck in an infinite loop. This has been fixed by splitting words in the middle if needed.

Fixes: #1987 (closed)