Escape code generator default string

slick-codegen/src/main/scala/slick/codegen/AbstractSourceCodeGenerator.scala

@@ -170,7 +170,7 @@ class $name(_tableTag: Tag) extends profile.api.Table[$elementType](_tableTag, $
      }
      def defaultCode = {
        case Some(v) => s"Some(${defaultCode(v)})"
        case s:String  => "\""+s+"\""
        case s:String  => "\""+s.replaceAll("\"", """\\"""")+"\""
        case None      => s"None"
        case v:Byte    => s"$v"
        case v:Int     => s"$v"

slick-testkit/src/codegen/scala/slick/test/codegen/GenerateMainSources.scala

@@ -126,6 +126,25 @@ val  SimpleA = CustomTyping.SimpleA
          | DBIO.seq( schema.create )
        """.stripMargin
    },
    new Config("MySQL1", StandardTestDBs.MySQL, "MySQL", Nil) {
      import tdb.profile.api._
      class A(tag: Tag) extends Table[(String)](tag, "a") {
        def quote = column[String]("x", O.Default("\"\"")) // column name with double quote
        def * = quote
      }
      override def generator =
        TableQuery[A].schema.create >>
        tdb.profile.createModel(ignoreInvalidDefaults=false).map(new MyGen(_))
      override def testCode =
        """
          |  val a1 = ARow("e")
          |  DBIO.seq(
          |    schema.create,
          |    A += a1,
          |    A.result.map { case Seq(ARow(quote)) => assertEquals("e", quote) }
          |  ).transactionally
        """.stripMargin
    },
    new UUIDConfig("Postgres2", StandardTestDBs.Postgres, "Postgres", Seq("/dbs/uuid-postgres.sql")),
    new Config("MySQL", StandardTestDBs.MySQL, "MySQL", Seq("/dbs/mysql.sql") ){
      override def generator: DBIO[SourceCodeGenerator] =