Revamped source tree traversion
* this was done to be able to implement directory symlinking
* the generation process is now split into three transformations
** the actual work is performed by "list.xsl" and "traverse.xsl" respecitively
** "make.xsl" wraps these two transformations
*** i.e. generation is now launched by executing "ixslt --transformation make.xsl"
* checked background images into VCS