Strip "unsafe" chars from <title> and other metadata

[bakert]

Like og:description. Anything in the head.

We can do this in quite a simple way OR store which font we use for each character (decided in fonts.py) in some way that can be accessed programmatically and use that to say "this is an emoji/symbol that should be stripped" versus "this is a 'normal character' that can be allowed". This would avoid stripping Japanese, Chinese, etc.

But both Google search results and Chrome browser tab will display a big yellow emoji for most emojis which we don't want so don't send in that way.