3.0 improvements needed

[Dmitry Iv.]

• More up/down shifts via accents, at least till 50.
• Latin-Ext range for Low-align, Cyrillic range for Center-align, see #21 (comment) for argumentation
• Latin/ASCII cover 52 chars - it seems to be very natural expectation.
• Embed last-resort blank font into wavefont to avoid CSS fallback. faster to have sync fallback and build wavefont upon it.
• WGHT and WDTH are useful as separate properties. Unlike tracking, WDTH stabilizes advance width as absolute value, so weight can safely be changed within the allocated stride.
• char should be left-aligned within width, not center-aligned.
• Map axes to standardized names - SOFT.
• ~~pass fontbakery tests #14 ~~
• +-10 y-shift accents #19
• expose meaningful JS API
• ~~demo with painter #27 ~~
• Limit weight to 400 (no sense to have it too big, besides that's standard value for Google Fonts).