white spaces are relevant in the XML file
(xml-parse-file): Do not kill an existing Emacs buffer if the file
to parse was already edited. This allows for on-the-fly analysis
of XML files
(xml-parse-tag): Check that the casing is the same in the start
tag and end tag, since XML is case-sensitive. Allows for spaces
in the end tag, after the name of the tag.
(xml-parse-attlist): Allow for the character '-' in the name of
attributes, as in the standard http-equiv attribute Do not save
the properties in the XML tree, since they are not relevant
