Major software components of the PyWrapper. Often they are represented by a single class - sometimes not.

   * CGI Instance component
   * Logging object: used everywhere to keep diagnostics and debug data, to write log files, ect.
   * TableGraph: A graph object representing the database schema
   * View object.
   * Datasource configuration: mappings, database connection/structure, wrapper settings
      * [[http://ww3.bgbm.org/viewcvs/viewcvs.cgi/biocase/tapir/pywrapper/config/schemas/local/www.biocase.org/schemas/datasourceprefs/1.0/index.xsd?view=markup][xml schema]]
   * Filter expression parser & evaluation