Log message:
fonts/gerb: import package

gerb: a font editor in gtk3 and Rust.

gerb is a GUI font editor and IDE. It is not production ready, but all the
basics are implemented.

It uses the UFOv3 format and can import:
 - UFOv2 directories
 - Glyphs files

and export:
 - OpenType files (.otf)
 - TrueType files (.ttf)