Support for emojis and fallback character

[patorjk]

This will be for version 1.12.0. What's here:

• Support for emojis. Currently no font supports emojis, but it's theoretically possible given what the spec says. While working on a FIGlet font editor I discovered this library didn't handle emojis. It's a bug but it effects none of the included fonts since none of them have emojis. However, since it's possible I'm fixing the issue.
• Support for the "missing character" glyph. The FIGlet spec notes that a missing character can be defined. Only 3 fonts implement this feature (Morse, Morse2, and Bigfig). Essentially if someone types a character not defined in the file (like an emoji) this character will be printed rather than nothing. Since adding this is like adding a new feature I'll bump the minor version for it.