Failure to cache time-dependent chart data

[grassick]

Charts with "Days since" or similar expressions that use the current time and date aren't cached properly, as each query looks different!

Ideas:

• Switch to now() type function
• No other ideas right now....

[grassick]

Affected operators are:

• future
• notfuture
• dayssince

All three could use the to_json(now() at time zone 'UTC')#>>'{}' trick, but does mean adding "at time zone" function to jsonql.