Changed some as of now unnecessary modifiers

The abstract makes sense, and I don't think the
final does make much...
Fix #565 Alternative budget now works properly.

There were two mistakes here. First, we weren't
opening the right record, as its number was not
being translated from table model to source model.
Second one, we had to insert a blank row for each
new alternative, so we can open the form.
Comunidades implicadas table behaviour improved.

Now the comunidades implicadas table doesn't delete
and insert everything each time, it creates, updates
and deletes as needed by each row.
Also removed come columns from the table and fixed
other problems.
Cancel should also close this dialog...