Marquee bug with periods

[makermelissa]

I was aware of this issue and I thought it was the HT16K33 library causing this. However after diving into the HT16K33 library, I now know it's because the HT16K33 library handles periods different than other characters in that it just lights up the dot instead of removing the character. This is a pretty simple fix, but thought I'd create an issue to attach.