add a new method which averages out a dg function in order to obtain a p1 function.  This is used to pass Neumann data coming from a rod to the hierarchic error estimator

[[Imported from SVN: r1866]]

[[Imported from SVN: r1790]]

[[Imported from SVN: r1651]]

[[Imported from SVN: r1638]]

[[Imported from SVN: r1607]]

[[Imported from SVN: r1603]]

[[Imported from SVN: r1592]]

[[Imported from SVN: r1563]]

[[Imported from SVN: r1552]]

add verification code to check whether the output pressure field really has the wanted total force and torque

[[Imported from SVN: r1544]]

[[Imported from SVN: r1535]]

[[Imported from SVN: r1534]]

[[Imported from SVN: r1033]]