Benchexec

- The supplied file `benchexec-cgroup.service` for cgroup configuration
on systems with systemd now works with systemd 240 or newer
(e.g., on Ubuntu 20.04).
This also affects the Debian package of BenchExec.
- Error messages about failed cgroup access were improved.
- Buttons below plots in the HTML table do not need to be clicked twice.
- Directly opening the quantile tab of HTML tables via the URL works now.
- First line of logs shown in overlay of HTML tables is selectable again.

This release brings several improvements for the new kind of HTML tables
produced by `table-generator`, in particular:

- Add hash routing, i.e., the possibility to navigate to certain parts
of the application directly by adding a suffix to the URL.
For example, opening `...table.html/table` will directly open the table.
While navigating through the application, the URL automatically adjusts.
This also means that it is possible to use the "Back" button of the browser
for going back to previously opened tabs or for closing an overlay window.
Thanks [DennisSimon](https://github.com/DennisSimon) for this!
- Make references to files in task-definition files clickable.
When clicking on a cell in the first column of table,
it shows the task-definition file in an overlay.
Now the file's YAML content is parsed and links to input files are added.
Thanks [lachnerm](https://github.com/lachnerm) for this!
- Fix filtering of negative values in half-open intervals.
- More tooltips and hover effects on table headers to improve usability.
- The table tab now appropriately adjusts if the browser window is resized.
- Fix legend of quantile plot if some columns are empty/missing,
and show disabled columns in gray.
- Fix scatter plot if not all data points have valid values.
- Fix layout of column-selection dialog in case not all columns are present
for all run sets.
- Fix scrolling behavior of close button of overlay windows.
- In case the property is the same for all tasks of a table,
it was not shown so far in the table. Now we show it on the summary tab.
- Improve position of scroll bars across all tabs.

There are also a few changes in other parts of BenchExec:

- Fix mount problems in container mode if mount points with unusual characters
(like `:`) or bind mounts over files exist.
The latter is for example relevant when nesting containers
(inside another BenchExec or Docker container).
- Several new tool-info modules and small improvements to existing ones.
- `runexec` now creates parent directories of output files if necessary.
- `table-generator` now works if environment variable `LANG` is missing.
- `table-generator` should now work on Windows.
- It is possible to turn off colored output on stdout by setting the
environment variable `NO_COLOR` (cf. https://no-color.org/).
- In the `contrib` folder, we now provide a script for generating
task-definition files in YAML format for old-style tasks.

This release does not contain any changes to BenchExec itself,
just for a script in the `contrib` directory.

This release contains only a small improvement of one tool-info module.

- A complete rewrite of the HTML tables produced by `table-generator`.
The tables are now based on [React](https://reactjs.org/), load much faster,
and provide features like pagination, sorting, and more intuitive filters.
More information can be found in [PR 477](https://github.com/sosy-lab/benchexec/pull/477).
Thanks [bschor](https://github.com/bschor) for this!
Note that the tables are not usable without JavaScript anymore.
The old kind of HTML tables can still be produced with the command-line flag
`--static-table`, but this is deprecated and will be removed in BenchExec 3.0
in January 2020 (cf. [479](https://github.com/sosy-lab/benchexec/issues/479)).
- Recursively clean up cgroups after a run.
This enables nesting `runexec` in itself,
but only if `--full-access-dir /sys/fs/cgroup` is passed to the outer `runexec`,
which means that the processes in the outer container have full access
to the cgroup hierarchy and could use this to circumvent resource limits.
- `benchexec` filters the tasks to execute depending on the expected verdict,
if `<propertyfile expectedverdict="...">` in used the benchmark definition.
- BenchExec now stores a timestamp for the start time of each run,
and timestamps for start and end of reach run set.
- `benchexec` will store arbitrary user-defined text as benchmark description
together with the results if specified with `benchexec --description-file ...`.
- Support for execution on Python 3.8.
- Fix crash in `runexec` if the tool's stdout/stderr contain invalid UTF-8.
- Fix hanging `benchexec` in container mode if tool cannot be executed
(e.g., if executable is missing).
- New tool-info modules and updates for SV-COMP'20 and Test-Comp'20.