Pysaga-cmd

- Progress bar now shows the elapsed time;
- Fixed typo in io_gdal execution aa9d9c6 (line 888);
- Fixed vector formats bug d575871 0d17917.

- There was an error on Windows regarding NamedTemporaryFile which d7bbd00 fixed. I had to add a delete=False parameter to unlock the file on Windows. From now on I will also test PySAGA-cmd on windows before every release.
- On Windows, the command prompt should not randomly open anymore while a SAGA command runs 3f6e20e.
- Added the possibility to convert the raster to an xarray DataArray ce6f9b0.

- Fixed README.md. This was needed because the example was wrong on pypi website;
- Added a progress bar when executing tools.


- Extra dependencies are now lazily imported in each function or method;
- Tools now, by default, raise errors when stderr is not empty. This behavior can be silenced with the ignore_stderr parameter;
- The ToolOutput has more functionality to it. You can now access the "rasters", "vectors" and "files" properties. Check out the 4th cell in this [notebook example](https://github.com/alecsandrei/PySAGA-cmd/blob/master/examples/notebooks/02_How_to_run_tools_and_plot_results.ipynb).
- Improved type hinting throughout the package;
- You can see which file extensions are allowed by GDAL using the "get_raster_formats" and "get_vector_formats" methods on the SAGA object.

- Added a get_sample_dem function in utils;
- Non-existing directories are skipped when searching for saga_cmd;
- Added better type hints for ToolOutput.

Fixed MacOS saga_cmd search bug.