Removed attributes and methods that were responsible to control columns/

Added attributes and methods on table to control indexes of relationship
added columns and constraints.
Create routine to restore columns/constraints positions.
Fixes the bug that was changing the columns positions whenever a
relationship was edited on the model (issue #449).

Custom  indexes for columns and constraints added by relationships are
now stored on tables. In previous version the relationship was the
responsible for that but this approach was wrongly provoking the bug
related on issue 449.

Remove unused parser attributes and commented old code.
Minor improvement on Table::restoreRelObjectsIndexes()
Merge branch 'fix449-cols-custom-pos' into develop