filters use valuecalendar and targetcalendar instead of calendar

[alexcjohnson]

Changes filter attribute calendar to valuecalendar and adds a new one targetcalendar to use if an array is provided as target. If target is a string (ie referring to an attribute in the same trace) it will ignore targetcalendar and instead use the calendar for that attribute (so xcalendar if target is 'x') which is what it was doing previously.

• hmm, maybe we should still allow targetcalendar to be specified, like if you're filtering on text or something that doesn't have its own calendar attribute? yeah, I'll do that.

Note that this is a BREAKING change (calendar if supplied is not coerced into valuecalendar) but only breaking what's been in master for the last 6 days since merging #1220

@VeraZab @cldougl @chriddyp @etpinard

[alexcjohnson]

added cleanData step to turn calendar into valuecalendar for backward compatibility

[etpinard]

💃