PDI-9848 - Mappings destroy metadata (when the Mapping input specification does not include all fields)

There are fix and unit tests.
[PDI-7741] - Modifying export to slave server to use post instead of put (put causes problems within tomcat as we only implement doGet and doPost)
Merge pull request #280 from TatsianaKasiankova/PDI-9848

PDI-9848 - Mappings destroy metadata (when the Mapping input specificati...
Merge pull request #319 from brosander/PDI-7741

[PDI-7741] - Modifying export to slave server to use post instead of put...
PDI-11363 - Database Lookup Step Performance Degraded in 5 vs 4.4.0.2

junit added
PDI-11363 - Database Lookup Step Performance Degraded in 5 vs 4.4.0.2

When using getLookup calls there is no need to make attempt to retrieve
row set metadata for every call. That may bring performance penalty
depends on jdbc driver implementation. For some drivers that penalty can
be huge (postgres).
During the execution calling getLookup() method we changing usually only
lookup where clause which will not impact return row structure.
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-8871 Get data from XML: Can't close error dialog Can not get fields