Batch of various tiny fixes:

• Replace first Windows occurence with trademarked entity
• Add trademark info for Microsoft Windows and Symantec Ghost.
• Replace "FreeBSD" with &os; and "ports collection" with &ports;, to keep the capitalization consistent. Also introduce an &os.ports; entity, which expands to "FreeBSD Ports Collection", to uniformly refer to the Ports
• Add <emphasis>, <application> and <quote> tags here and there
• Use manpage entities, instead of <literal> for FreeBSD command-line utility references
• Various minor grammar and syntax nits