Support for + operator (Extended Relational Algebra)

[lcmarquez2005]

The ability to sum two columns and given a column result, like relational algebra.

Example: Π atribute1, atribute2, (atribute1 + atribute2 → sum_atributes) (table) Another Example: Π table1.atribute1, table2.atribute1, (table1.atribute1 + table2.atribute2 → sum_atributes) (table1 ⨝ table2)

[rlaiola]

This featured is already available. Here is an example using the UIBK - R, S, T database:

π a+d->sum (R ⨯ T)

[lcmarquez2005]

Oh yeah, thank you so much, great project btw!!, i liked it