Vsevolod Romashov

Исправляет текущую стоимость валюты - как в `portfolio_table`, так и при подсчёте `total_amount`.

Postgres [allows](https://www.postgresql.org/docs/9.4/sql-alterindex.html) renaming indexes, and while it is impossible to use inside the schema diffing algorithm (as indexes are compared by name) it can still be used inside conditional migrations....

If the database schema contains any check constraints that mention an enum field, then running `AlterEnumValues` against that enum type fails. A possible solution would be to drop check constraints...