PDI-10420, PDI-10419 - add help button, modify help dialog

 + Added help button to XUL based step/job entry dialogs
 + Add Help to context menu for steps/job entries in View tab in Spoon
 * Show error message dialog if the documentation for step is not found
 * Show web help after user click Help button/ctxt menu item
PDI-10996 - Concurrent shell script job entries can cause java.util.ConcurrentModificationException
Merge pull request #302 from askdzmitry/PDI-10420

PDI-10420, PDI-10419 - add help button, modify help dialog
Merge pull request #318 from askdzmitry/PDI-10996

PDI-10996 - Concurrent shell script job entries can cause java.util.ConcurrentModificationException
Merge pull request #321 from prakapenka/PDI-11363

PDI-11363 - Database Lookup Step Performance Degraded in 5 vs 4.4.0.2
[PDI-11478] - Adding rep.readSharedObjects() call to TransSplitter constructor, unit test
Merge pull request #323 from brosander/PDI-11478

[PDI-11478] - Adding rep.readSharedObjects() call to TransSplitter const...
PDI-11103 - Performance of Sort Rows step in 5.0

junit tests added
PDI-11103 - Performance of Sort Rows step in 5.0

refactor existing code, perfomance restored.