Refactor and lint

[Sasszem]

• [ ] review menu styles, and refactor them
• [ ] refactor common strings, such as font paths
• [ ] refactor global constants from Config into globals
• [ ] remove globals pollution (selectLang, globalvars, rwrc)
• [ ] rename Config
• [ ] lint with luacheck

[Sasszem]

Also:

• [ ] remove love.js support code

[Sasszem]

Most of this can be done by you, @Btimes2