Add font editor

[cwensley]

In PabloDraw DOS, it had the feature to edit fonts quite easily. This is especially useful for formats like XBin. One of its cool features was being able to edit multiple characters as "one", so you can create a larger image than just one character at a time.

A font editor should be added which should have a way to modify characters, and import and export .fnt files.

[ericolito]

Yes please! That would be awesome.