Ignore letter case in log filters and rule conditions

Text filters in the Stream, such as contains, starts-with, and ends-with, now ignore letter case. Use contains-cs, not-contains-cs, starts-with-cs, or ends-with-cs when case must match exactly. New rule conditions also have Case Insensitive turned on by default. See Match letter case exactly.

User agent conditions now support exists and missing, so you can match requests that do or don't send a User-Agent header.