#376: Enable multiple versions of lbaf to run in the same python environment

[tlamonthezie]

Fixes #376

This PR

• Restore the way to run LBAF not as a package. When package is not installed then the lbaf module will be resolved relative to the current project directory automatically.
• For users who want to run development mode using lbaf as a package they will have to run pip install -e . since it has been removed from requirements.txt
• README.md file has also been re-worked to explain how to use lbaf as a package & adds information about using virtual environments
• Tests are again run against the lbaf source directory (no more the package installation because it may not be installed as a package now)

[nlslatt]

This did not fix my problem. I tried uninstalling LBAF, checking out your branch, and running LBAF there, but got the same error as before:

Traceback (most recent call last):
  File "/Users/nlslatt/work/LB-analysis-framework/src/lbaf/Applications/LBAF_app.py", line 13, in <module>
    import lbaf.IO.lbsStatistics as lbstats
ModuleNotFoundError: No module named 'lbaf'

[tlamonthezie]

This did not fix my problem. I tried uninstalling LBAF, checking out your branch, and running LBAF there, but got the same error as before:

Traceback (most recent call last):
  File "/Users/nlslatt/work/LB-analysis-framework/src/lbaf/Applications/LBAF_app.py", line 13, in <module>
    import lbaf.IO.lbsStatistics as lbstats
ModuleNotFoundError: No module named 'lbaf'

@nlslatt Sorry there was an remaining invalid path in LBAF_app.py. This should be better now. Could you please retry ? (for LBAF application you can also just run python src/lbaf)

[nlslatt]

@tlamonthezie @ppebay This works for me now. Thank you