Add missing entities to the PartKeepr class.
typo.
Set pdf margins to 0, this will prevent problems with barcodes or text on the borders.
Moves every printing renderer to a specific directory.

Additionally removes the if(..) return from the PDFDefaultRenderer.
The next step will be to move the directories out of the partkeer tree and
add symlinks to them.

refs #283
Move the rendering stuff to a directory outside of the main PartKeepr searchpat.
This will temporally disable these renderer, but they can simply reactivated
by adding a symlink to the moved directory if needed.

refs #283