Support styled text in titles

[mfenner]

As we are using CSL (Citation-Style Language) to store and display works, we should also support styled text in titles using the CSL approach: http://citationstyles.org/downloads/upgrade-notes.html#rich-text-markup-within-fields

• <b> - bold
• <i> - italics
• <sc> - small-caps
• <sub> - subscript
• <sup> - superscript

<sc> is obviously not a proper HTML tag, and should be displayed as <span style="font-variant: small-caps;">Text</span>.

To implement this we need to:

• support styled text in our import filters
• don't strip out those tags when we sanitize the title
• display styling correctly in the frontend