querying on specific values should be smart to handle precision issues

[havok2063]

Is your feature request related to a problem? Please describe. Trying to perform a query on specific values, e.g. RA and Dec doesn't work when the precision is slightly off.

Querying on this RA, Dec does not work: RA,DEC = (229.52558, 42.745842) But this one does: RA, DEC = (229.525575871, 42.7458424664) in q = Query(searchfilter='cube.ra == {0} and cube.dec == {1}'.format(RA,DEC))

Describe the solution you'd like Queries should be smart to some level of precision handling of values. Querying on exact values will probably be rare in practice, but it would be nice to be able to do it.