extractEqualConditions() Extract conditions of the form "column name = value" and "column name1 = column name2" that can be used
in order to optimize a mandarax query.
Extract conditions of the form "column name = value" and "column name1 = column name2" that can be used
in order to optimize a mandarax query. These conditions are removed from the list of conditions (if any,
must be connected with AND).
TODO: full normalization of AND/OR/NOT connectives !!
a list of equals conditions