Cleaned up XML tag mess: - all of <parameter> and <code>, and some of <dirname>, <value>, and <command> were replaced by <literal>; - the rest of <dirname> were replaced by links; - <argument> were replaced by <value>; - <value> is now rendered in HTML in italic; - <literal> and <path> can now contain <value>. Cleaned up terminology mess: - directives take "parameters".