tsvread: importing tab-separated data

Both numeric and text is imported. For the non-numeric cells, the numeric values are NANs.
There are several options, depending on the input and output arguments. If no output arguments are requested, the data is displayed to the screen. It is a good idea to verify the import by using the no-output option. It is possible to import selected columns by specifying the header string. If no header strings are supplied, then the entire spreadsheet is imported.