- Added synonym support
- Added option to keep duplicate terms

Allows simple parse call:
taxonomy_xml_parse($xml); as opposed to taxonomy_xml_parse($xml, 0);

Now outputs a message using drupal_set_message() instead of returning output.

TODO: fix vocabulary-node association: wrong node types??
TODO: fix GLOBALS variables Name (use standard notation)

- import: checking if term already exists using name and hierarchy
  - import: using file_read_contents() instead of using file handlers
  - export: default filename is "taxonomy_VocabularyName.xml"
  - export: XML is more human-readable: added indents and line feed
- export: using $_SERVER[] superglobal for browser checking
  - displayed information on import process
    - displayed warning if non vocabulary is present
    - Fixed some help text (export)