Combine full packages

[remram44]

Currently, we can combine trace databases pre-packing using reprozip combine (#183).

There could be a way to combine different RPZ files into a single one (with multiple runs). This entails:

• Merging the traces (done by Merge traces #183)
• Merge the configuration files (keep architecture & version, additional files, modified run argv, env, id, input/output files...)
• Merge files (show an error if a file appears in multiple packages with different content)

[remram44]

Needed by ReproNim/neurodocker#69