* "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

* transformations contain one or more "datasource" meta nodes
** these nodes define the required datasources
** up until now it was required to define the whole path to the file to be loaded
* the implementation of directory linkage in b942f8e removed the underlying need for providing the source / target prefix
** this commit now updates the generation transformations to match this change
*** this simplifies the datasource definition process for the end-user
*** additionally it makes the target / source directories easier to maintain
* changed cleanage task implementation to remove the whole directory and recreate it from scratch
** otherwise directory linkage and in turn the whole generation failed when the target directory did not exist in the first place
* removed task reordering in the process transformation
** tasks are now processed exactly as they were scheduled
** this was changed so that e.g. the "00_content" directory is linked before the first datasource is required

* random sort order of page-entries on category pages led to unsatisfing results
* the entries are now sorted in an alternating fashion depending on their digest length
* this produces a much more consistent and balanced output

* expanded "02_data/pages.xsl" transformation to include pages in subfolders
* "03_meta/categories.xsl" transformation generates a categorized view of all pages simmilar to the one provided for tags by "03_meta/tags.xsl"
* "99_result/category/category.xsl" transformation generates category overview pages
* added basic project related pages inside the "projects" category

* the output node is defined in both the master and datasource transformation
** i.e. they do not have to be defined in transformations making use of one of these transformations

* paginates article datasource into chunks of two articles
** this is needed to generate a normal blog article stream
** includes index and total pages for each page entry
* to be resolved against the normal article datasource

* this is needed for the implementation of a article datasource grouped by year
** this in turn is needed for the archive page template
* modified tags meta transformation and article result transformation accordingly

* xalan and/or InputXSLT namespace should only be included when they are actually required

* merges the content of the "00_content/meta.xml" file with additional data such as the available tags
* simplifies providing a basic datasource to every result transformation
* modified master, article and tag page template accordingly

* contains tags and their articles but no further article data
* the unaugmented tags datasource is merged with article data on the metadata level

* this was done to simplifiy support data queries while resolving the main datasource

* added "tags.xsl" meta datasource
** augments tags and their articles extracted from the content tree with article data from the article datasource
* added basic tag page template
* renamed "pages" directory to "page" as it is more intuitive from a user perspective