Use this script if you want to quickly calculate the totals of some
query across all the queries in a MRVA run.
For an example of such a query, see e.g.
`python/ql/src/Metrics/Internal/TypeAnnotations.ql`
The script expects the query to produce an output table of the form
```
| header0 | header1 | header2 | header3 | ...
|----------|----------|----------|----------|----
| message1 | value11 | value12 | value13 | ...
| message2 | value21 | value22 | value23 | ...
...
```
where all of the `values` are numbers. For each `(message, header)`
pair, it then calculates the total of all the values in that cell,
across all of the repos in the MRVA run.
To use the script, simply pass it the URL of the exported Gist of the
MRVA run. After calculating the totals, the script will then
(optionally, but by default) add the totals to the `_summary.md` file,
and push these changes to the Gist.
