Removed need for prefixing datasource source attribute
* 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