fixed error handler that suppressed most Tcl errors
> 2 cores per side work again, but LE is broken
Added Achims version of the Krüger bending (remove Wolfgang later on)
Added IBM docu to the User's Guide
Tightened the conditions for Lees-Edwards
Merge branch 'master' of github.com:espressomd/espresso into ibm
Merging docu for IBM
Fixed docu of ibm