handbook/*

• Use trademark entities, including XFree86 now that the XFree86 Core Team has responded with their trademark policy.
• Add trademark attributions.
• Always use correct case for trademarks.
• Don't join trademarks with other words, e.g. using hyphens.
• Don't use trademarks as nouns (e.g. don't use "Windows NT's").

trademark.ent:

• Add entities for more trademarks / companies.
• Fix the Xiph.Org entry.