data: set default field for lowestByDate() and highestByDate()

Set default field for lowestByDate() and highestByDate() as 'Close'.

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>
strategy:turtle: update run() method

Ignores the first 10 days even though some of these days may match
long/short signals.

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>