added pattern tableau for conditional unique column combinations

added pattern tableaus as display type for conditional uniques

Small fix in ColumnCombinationBitset where a ImmutableList was expected but the current Implementation is a List. Missing change after refactoring in the main repository.

Add a clone() method for PositionListIndex, which is a deep copy.
I just checked multiple possible solution and most of them do not work. The only possible solution left is writing server and client specific code using super-source/emulated source directories. This may have a huge impact on project structure, so I will stick with "\n" as newline character for now.

A future version of GWT will support System.getProperty("line.separator"), which will fix this issue.