correct the direction of the two port, edit the examples accordingly and handle the fixme of mathadon.
Merge pull request #2 from Mathadon/issue54_addBorefieldModel

removed absolute pressure from GroundHeatExchanger model
Merge branch 'issue54_addBorefieldModel' of https://github.com/damienpicard/IDEAS into issue54_addBorefieldModel
adapted borefield so that other packages can also contain source files for running ShortTimeResponseHX