PIG-3809: AddForEach optimization doesn't set the alias of the added foreach (cheolsoo)


git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1577961 13f79535-47bb-0310-9956-ffa450edef68
PIG-3753: LOGenerate generates null schema

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1577975 13f79535-47bb-0310-9956-ffa450edef68
PIG-3805: ToString(datetime [, format string]) doesn't work without the second argument

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1577979 13f79535-47bb-0310-9956-ffa450edef68