Revamped transformation layout to remove need for the "01_files" level
* "01_files" contained a single "source" transformation which listed the contents of the "00_content" level
** this was unnecessary as the base "list" transformation already lists the contents of all levels
* added new "expression" mode to datasource meta tag processing in the task processing transformation
** this expression modes allows for the evaluation of arbitrary XPath statements
*** e.g. a query to the results of "list.xsl"
* modified base transformation datasource structures to include the level and meta tree
* modified all existing content transformations to query the level-tree instead of the deprecated "source.xml"
** i.e. XPath statements
** the main change is that directories are available as "directory" nodes instead of nodes named by the directory name
* these changes where implemented to simplify the architecture and to increase flexibility