func AddMigration(up, down rockhopper.TransactionHandler) {
	pc, filename, _, _ := runtime.Caller(1)
	funcName := runtime.FuncForPC(pc).Name()
	lastSlash := strings.LastIndexByte(funcName, '/')
	if lastSlash < 0 {
		lastSlash = 0
	}
	lastDot := strings.LastIndexByte(funcName[lastSlash:], '.') + lastSlash
	packageName := funcName[:lastDot]
	AddNamedMigration(packageName, filename, up, down)
}
AddMigration adds a migration.
package mysql
import (
	"fmt"
	"runtime"
	"strings"
	"github.com/c9s/rockhopper"
)
var registeredGoMigrations map[int64]*rockhopper.Migration
func Migrations() rockhopper.MigrationSlice {
	var migrations = rockhopper.MigrationSlice{}
	for _, migration := range registeredGoMigrations {
		migrations = append(migrations, migration)
	}
	return migrations.SortAndConnect()
}