Remove dead code

[woutdenolf]

The project is full of dead code

• if 0:
• code after return
• ...

Every line of code is maintenance burden: #1205 (comment).

I propose to remove all dead code.

[sergey-yaroslavtsev]

Also:

if ...:
...
elif 1:
...
else:
...

[vasole]

Please, verify that the dead code does not play the role of documentation code. If that is the case, it should at least stay commented.

I recall in some cases unoptimized but easy-to-follow code was there to serve as explanation of used optimized code that was difficult to understand.