Is your feature request related to a problem? Please describe.
An ScmRun requires timeseries to be on the same timebase. This requires an expensive resample when joining different scenarios.

Describe the solution you'd like

An ScmEnsemble object which is a container for 1 or more ScmRun's. This object proxies commands like filter and timeseries to ScmRun and then combines the result.

There will be an implicit meta column to which will be unique for each ensemble member. This allows the unique identification of a timeseries.

Describe alternatives you've considered

Not requiring identical an identical timebase within ScmRun. This may be useful in future, but would not allow run-specific metadata i.e. magicc metadata to be associated with a set of output.