[[Imported from SVN: r1637]]

[[Imported from SVN: r1635]]

[[Imported from SVN: r1632]]

[[Imported from SVN: r1614]]

[[Imported from SVN: r1612]]

[[Imported from SVN: r1611]]

[[Imported from SVN: r1607]]

[[Imported from SVN: r1603]]

bugfix in getResultantForce: get index of correct cross-section orientation from the index set instead of having 0 hardwired here

[[Imported from SVN: r1594]]

[[Imported from SVN: r1592]]

[[Imported from SVN: r1590]]

[[Imported from SVN: r1563]]

[[Imported from SVN: r1554]]

[[Imported from SVN: r1553]]

[[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: r1529]]

[[Imported from SVN: r1528]]

[[Imported from SVN: r1525]]

[[Imported from SVN: r1524]]

[[Imported from SVN: r1510]]

[[Imported from SVN: r1506]]

[[Imported from SVN: r1505]]

Add a method to assemble the Hessian matrix by a finite difference
approximation.

[[Imported from SVN: r1504]]

[[Imported from SVN: r1503]]

[[Imported from SVN: r1502]]

fixed one indexing bug in the hessian computation; added various helper methods for the derivatives of the strains and fd approximations for them

[[Imported from SVN: r1501]]

[[Imported from SVN: r1495]]

[[Imported from SVN: r1494]]

[[Imported from SVN: r1473]]

[[Imported from SVN: r1472]]

[[Imported from SVN: r1471]]

[[Imported from SVN: r1470]]

[[Imported from SVN: r1469]]

[[Imported from SVN: r1468]]

[[Imported from SVN: r1220]]

[[Imported from SVN: r1206]]

[[Imported from SVN: r1124]]