mapswipe workers: stats calculation for footprint project type

[Hagellach37]

the "normal" statistics calculation needs to be adapted for the footprint project type.

First step would include to check the projectType and not execute all functions if it's a footprint project type. At a later stage we can add the functionality for this project type. But this can be addressed in another issue.

2020-10-12 17:28:11,260 - INFO - project_stats.py - get_per_project_statistics - saved project stats by date for -MGitNLNGnlFp23xr2EU: /root/.local/share/mapswipe_workers/api/history/history_-MGitNLNGnlFp23xr2EU.csv
Traceback (most recent call last):
  File "/usr/local/bin/mapswipe_workers", line 33, in <module>
    sys.exit(load_entry_point('mapswipe-workers==3.0', 'console_scripts', 'mapswipe_workers')())
  File "/usr/local/lib/python3.6/dist-packages/Click-7.0-py3.6.egg/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/Click-7.0-py3.6.egg/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.6/dist-packages/Click-7.0-py3.6.egg/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.6/dist-packages/Click-7.0-py3.6.egg/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.6/dist-packages/Click-7.0-py3.6.egg/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/Click-7.0-py3.6.egg/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/mapswipe_workers.py", line 380, in run
  File "/usr/local/lib/python3.6/dist-packages/schedule-0.6.0-py3.6.egg/schedule/__init__.py", line 466, in run
    ret = self.job_func()
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/mapswipe_workers.py", line 377, in _run
  File "/usr/local/lib/python3.6/dist-packages/Click-7.0-py3.6.egg/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/mapswipe_workers.py", line 130, in run_generate_stats
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/mapswipe_workers.py", line 135, in _run_generate_stats
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/generate_stats/generate_stats.py", line 54, in generate_stats
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/generate_stats/project_stats.py", line 377, in get_per_project_statistics
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/generate_stats/tasking_manager_geometries.py", line 438, in generate_tasking_manager_geometries
  File "/usr/local/lib/python3.6/dist-packages/mapswipe_workers-3.0-py3.6.egg/mapswipe_workers/generate_stats/tasking_manager_geometries.py", line 32, in load_data
IndexError: list index out of range
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