Redeclared functions in examples directory cause failures with `go get ....` command.

The following command:

```bash
~ $ go get ...
```

fails with:

```bash
~ $ go get ...
# github.com/ziutek/mymysql/examples
github.com/ziutek/mymysql/examples/long_data.go:25: main redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/database_sql.go:10
github.com/ziutek/mymysql/examples/parallel.go:27: main redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/long_data.go:25
github.com/ziutek/mymysql/examples/prepared_stmt.go:10: printOK redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/long_data.go:14
github.com/ziutek/mymysql/examples/prepared_stmt.go:14: checkError redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/long_data.go:18
github.com/ziutek/mymysql/examples/prepared_stmt.go:26: main redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/parallel.go:27
github.com/ziutek/mymysql/examples/reconnect.go:11: main redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/prepared_stmt.go:26
github.com/ziutek/mymysql/examples/reconnect.go:103: checkErr redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/parallel.go:21
github.com/ziutek/mymysql/examples/simple.go:10: printOK redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/prepared_stmt.go:10
github.com/ziutek/mymysql/examples/simple.go:14: checkError redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/prepared_stmt.go:14
github.com/ziutek/mymysql/examples/simple.go:22: checkedResult redeclared in this block
        previous declaration at github.com/ziutek/mymysql/examples/prepared_stmt.go:21
github.com/ziutek/mymysql/examples/simple.go:22: too many errors
```