Fix #526: add book titlepage for TRD stylesheets

[tomschr]

Identical with a SBP article titlepage. The following elements are shown in this order:

• d:title, d:info/d:title
• d:subtitle, d:info/d:subtitle
• d:info/d:meta[@name='series']
• d:info/d:meta[@name='category' or @name='type']
• d:info/d:authorgroup
• d:info/d:author
• d:info/d:cover
• d:info/d:meta[@name='platform']
• d:info/d:date
• d:info/d:abstract
• d:info/d:copyright

[tomschr]

I've tested it and it looks good. Let's merge it.