[#230] introduced ColumnPermutations
#90 Add method to get number of skipped differing lines.
Merge branch 'master' into FileIterator
Merge branch 'master' into FileIterator
Merge branch 'master' into FileIterator
#232 Add subset symbol between the column combinations to make the sides clear.
#188 Convert empty strings to null values using Collections.unmodifiableList.
#19 Algorithm can set accepted DB systems. Frontend filters the database connections.
Merge branch 'master' into Algorithm_DBSystem

Conflicts:
	frontend/src/main/java/de/metanome/frontend/client/input_fields/DatabaseConnectionInput.java
Merge pull request #249 from HPI-Information-Systems/listingOfINDs

#232 Add subset symbol between the column combinations to make the sides...
Merge pull request #242 from HPI-Information-Systems/FileIterator

File iterator
#231 added ColumnPermutation class to Metanome_Dependencies.gwt.xml
Merge pull request #250 from HPI-Information-Systems/Algorithm_DBSystem

#19 Algorithm can set accepted DB systems. Frontend filters the database...
Merge pull request #231 from fatschi/Issue#230

[#230] introduced ColumnPermutations