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libxml.lua
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mktree(), viewt(), mkidf(), mkxml()

These functions does not handle document oriented XML data.
They assume the XML data is data oriented, i.e., their nodes are simple one:
The nodes created by mktree() have elements described below.

Let's N be a node, then
N.name		-- name of the node
N.attrs		-- all attribute of the node; type(N.attrs)=="string"
N.attr[key]	  -- decomposiotion of N.attrs, key is the attribute name
N.parent	-- parent of the node
N[1],N[2],..,N[n]	-- children of the node, where n==#N
N.text		-- text data of the node. type(N.data)=="string"
N.no		-- array index of the node, which mean: N == N.parent[N.no]

Note that a document oriented XML data such that:
	<definition>A <em>computer</em> is blah blah ... </definition>
breaks the above assumption because this is not equivalent to
	<definition>A is blah blah ...<em>computer</em></definition>
