mvcombine <field> command

[tombonfert]

• The mvcombine command groups by all available columns except for <field> (input param), _time and _raw column. Subsequently, the command puts for each group the values of in a mvfield (array).
• Issue: With the current interface to SplToCatalyst there is no way to determine the available set of columns
• Solution: If mvcombine is not the first command of a search, we can apply it on the so far selected columns (this is currently implemented). However, IMO this solution is error-prone and will produce wrong results.