Re #760: Fixed obvious mistake in segmentations python test

Fixed #770: Fixed copying of segmentation nodes

Re #620: Minor fixes in subject hierarchy plugins

Re #760: Attempt to fix segmentations python test on Mac. It fails because when exporting a segment to model node, on Windows and Linux it has 588 polygons, but on Mac somehow it has 580

Re #760: Attempt to fix dose comparison generic widget test that failed on linux and Mac due to its high minimum width

Re #760: Fixed isodose logic test that failed due to color names issue introduced by Slicer rev24436

Re #760: Fixed memory leak that occurred when entering Segmentations module

Re #760: BatchStructureSetConversion now restores originally selected DICOM database. The test crashes on exit when being run as a test, but works fine when started from Slicer.

Re #760: Fixed BatchStructureSetConversion test that failed due to invalid download link (it may have changed due to Midas updates). Also fixed directory creation and logging call

Re #760: Removed duplicate developer section from DicomSroExport module widget

Re #767: Fixed does comparison test that failed because it used the new default setting for dose threshold

Re #760, re #766: Fix tests that failed due to recent changes regarding transform handling. One error source was that the bounding box transformed function TransformOrientedImageDataBounds did not handle non-zero extent starts. The other one was that in many places vtkGeneralTransform is passed as transform, and it was always handled as non-linear. However, it can also be linear transform if all concatenated transforms are linear. Now this is detected and the linear transform control branches are also hit.

Re #760: Fix tests that failed due to recent changes regarding observing master representation

Test #760: Added segmentation test case for import/export with transforms involved

Re #765: Added subject hierarchy plugins for External Beam Planning WIP3