Provide TSV (tab separated values) output formatter

[Johan Stenberg (ex-msft) (johanste)]

To use, specify --output tsv on the command line.

Behavior:

• Will print a single tab separated row of output values per result item.
• Objects of type List will print the number of items in the list
• Objects of type dict will be printed as {object}
• Simple value types will be printed

Rationale for implementation per above:

• In order to be useful, the output needs to have a fixed number of output columns
• Tab was chosen as separator since it is less likely to occur within a value (no escaping was implemented since that makes both the implementation harder, and - more importantly - consumption of the output significantly harder)

Combined with --query to get properties of nested children.