There can be gaps in the id column. This ensures that the id column is set to the max value

PostgresStORM+PickNextId.swift

import PostgresStORM

extension PostgresStORM {
	/// Set Next ID Value to MAX ID
	///
	/// This is a workaround for issue [ISS-546](http://jira.perfect.org:8080/browse/ISS-546)
	///
	/// When inserting new rows then I'm getting errors like this:
	///
	///     ERROR: duplicate key value violates unique constraint "president_key"
	///     DETAIL: Key (id)=(45) already exists.
	///
	/// I'm having gaps in my `id` column, eg: 1, 2, 3, 7, 8
	/// Because I have imported a dataset with gaps in the `id` column.
	func pickNextId() throws {
		let table = self.table()
		let statement = "SELECT setval('\(table)_id_seq', (SELECT MAX(id) FROM \(table)))"
		try self.sql(statement, params: [])
	}
}