Improve O or 0 and upright @

[geryogam]

Thanks for this very nice font! I have noticed two issues:

• the glyphs of Latin Capital letter O (U+004F) and Digit Zero (U+0030) look exactly the same;
• the upright glyph of At sign (U+0040) is based on the italic glyph of Latin Small Letter A (U+0061) instead of the upright glyph.