WIP: Font manager: Download from google loads all unicode variants

Basically, it’s correct—but it can quickly lead to confusion (take a look at a font like Noto Sans JP). See this thread on Facebook for more some details:

I think it would be sufficient to display a note that it can get pretty “wild” depending on the font. However, what we definitely need to take care of is the “old” custom font manager… which is a mess, due to the unicode ranges :v: