[com.google.fonts/metadata/fontname_not_camel_cased] expand check into general GF family name compliance

[yanone]

I'm going to rewrite the metadata/fontname_not_camel_cased check and make it into a name table check because I need this to be flagged when I work on it (when METADATA.pb doesn't exist yet usually), not when it's PR'd to GF (when it does exist).

In the same wake I want to expand the scope of the check to make sure the name complies with the guide. Here's what I infer from it:

• Allowed characters: A-Za-z0-9 and space
• Must start with A-Z
• No CamelCase
• No initials (like "PT Sans")
• (I'm not going to implement the "no references to languages or writing systems" rule)

And then the Guide says "no diacritics". Are we sure about that? No "Moiré", no "Straße", no "Fantômas"?
I mean, I scrolled GF manually half-way through and indeed couldn't find a single non-ASCII character in names, but still I need to ask.

Also I would create a known exception file again for abbreviations like we already have it for CamelCase names and put IBM, PT, SIL etc in it, but keep it concise.

The new check now finds a whole bunch of instances in the GF library where family names are written without spaces (=CamelCased) in the name table but with spaces in METADATA.pb (only guessing that this is the situation, I confirmed some names to be correctly displayed on fonts.google.com)