fixed relative import as well as baseflow doubling

[ErikNixdorf]

Fixes #8 and #7

[MarcoHannemann]

The imports are still not working, however renaming was succesful. What happens if you import as:

from bflow.bflow import compute_baseflow,add_gauge_stats,plot_bf_results

This works for me.

In the current form I still get errors:

Traceback (most recent call last):
  File "/home/hannemam/Projects/sbat/sbat/sbat.py", line 12, in <module>
    from sbat.bflow.bflow import compute_baseflow,add_gauge_stats,plot_bf_results
  File "/home/hannemam/Projects/sbat/sbat/sbat.py", line 12, in <module>
    from sbat.bflow.bflow import compute_baseflow,add_gauge_stats,plot_bf_results
ModuleNotFoundError: No module named 'sbat.bflow'; 'sbat' is not a package```

[ErikNixdorf]

I changed it by adduing the library path to pathlib in the _init.py, now both running sbat.pyas well as apply_sbat.pywork on my machine

[ErikNixdorf]

from my point of view this also closes #4