Extend the ? session selection syntax with support for time periods

[vkarak]

Currently, we cannot either select sessions based on a time period or a filter expression using the ? syntax. For the latter, not being able to filter also on time period is problematic, as it requires us to scan the whole DB for sessions. This can be time consuming. We propose to extend the ? with a time-period component that would limit additionally the query based on the time period. This will considerably speed up session queries based on arbitrary session information as we will only be decoding a subset of the stored sessions.