Adding support for Jungfrau .dat files (#152)

closes #150 

**Not addressed in this PR:** 

- pixels_per_frame, bytes_per_frame and tell should be made cost in
FileInterface

pyproject.toml

@@ -15,4 +15,9 @@ cmake.verbose = true
 [tool.scikit-build.cmake.define]
 AARE_PYTHON_BINDINGS = "ON"
 AARE_SYSTEM_LIBRARIES = "ON"
-AARE_INSTALL_PYTHONEXT = "ON"
+AARE_INSTALL_PYTHONEXT = "ON"
+
+[tool.pytest.ini_options]
+markers = [
+    "files: marks tests that need additional data (deselect with '-m \"not files\"')",
+]