Big Sign Writer

@DebornMC: Adds support for additional fonts

• 2 new default fonts: Sharp & Retro
• Additional custom fonts may be supplied by the user in config/bigsignwriter/fonts
• Base mod config moved to config/bigsignwriter/config.json

The default font has gained a few new characters

• New characters are now cleanly merged with user font overrides for default fonts

Base mod config can now be modified in-game when both YACL and Mod Menu are installed.

Contains a potential fix for #4 (Fonts being corrupted to question marks), however I cannot confirm it works as I have never been able to reproduce that issue.