changes recommanded by MW.
update examples of borefield models
add UsersGuide.mo and update singleUTubeResistances.mo and convectionResistance.mo according to the changes of Wetter.
Update of UsersGuide.mo and correction with scaSeg in SingleUTubeInternalHEX.mo
add documentation.
change icon od borefield package.mo
merge changes from upstream/master.
merge with upstream/master