[Big]: Layout controlled via TeX itself ...

New macro(s): \setPageBreaks{a,b,c,d ... }
Will trigger a \nextpg after the specified subparts

Page/Question/Subpart numbering reset within \DocAuthor itself
Removed textpos package ...

xstring is now includeded from with tufte-exam.cls itself
Question versions also being set by callbacks

Using list processing provided by etoolbox throughout, ie. for version setting and for page-breaking.