Remove unused import and variables from all modules.

[LordGameleo]

We are currently using a customized checklist for pylint. We have disabled a lot of checks to make our build successfully. We want to counter these checks few at a time. This issue deals with one of them.

How to produce:

After forking and cloning this repo, make a branch named develop-Pylint_rm_unused using
git branch develop-Pylint_rm_unused

Checkout branch by
git checkout develop-Pylint_rm_unused

remove unused-import, and unused-variable, from .pylintrc file (line 24)

Check pylint errors using
pylint * on terminal (in the repo)

Add doc strings to get a perfect 10 score on pylint.

[Rechi]

already done