[Therion] Aven colour by date and loop error

[Bruce]

>On Sun, Jul 06, 2014 at 02:23:41PM +1200, Bruce wrote:
>> Also, I presume that colour by date in Aven refers to 'survey date'.  
>> Is colour by 'exploration date' something that has been considered?
>
>It's whatever you put in the *date commands - that's expected to be the
survey date, but it isn't currently used for anything like >autocomputing
the declination.  But that doesn't really help if you want both dates
available.

In therion the date is used for survey date and explo-date is used for
discovery/exploration date.  In therion the date IS used to calculate
declinations where there is also a coordinate system specified.
It would be nice to maintain this level of compatibility across the two.

Bruce