files were declared with <?xml version="1.0" encoding="UTF-8"?>
but were definitely not UTF-8; corrected and added Unicode BOM
Linux-Networking.xml: fixed a doubly-closed </ulink>
Overview.xml: there were several large pasted sections of text which
contained characters understood to be markup; wrapped the entire
sections in <![CDATA[ ]]> blocks;
Protocols-Standards-Services.xml: closing </sect1> tags cannot have id="" on
them: removed these; wrapped several email addresses with <email/> to allow
validation; fixed tons of URLs with proper <ulink/> elements; wrapped a few
pasted sections in <![CDATA[ ]]> blocks;