[DBAL-237] Fix bug when removing and adding an index on the same columns that may be part of a foreign key.

[2.0][DDC-395] Applied the provided patch of Jordi Boggiano removing some trailing whitespaces and fixing missing public keywords

[2.0] DDC-169 - Add functionality to detect that an add + drop column diff is actually just a rename column.

[2.0] DDC-169 - Finalized implementation of Schema diff algorithm, added diffs of sequences and foreign keys. Fixed several bugs and changed the API of the Schema objects.

[2.0] - DDC-169 - Fixed another regression in refactored SchemaTool, began porting of eZ Components Database Schema Comparator, SchemaDiff and TableDiff.