Do not turn echo off for subsequent commands in batch activators (#2411)

[pawelszramowski]

Some @ are certainly unnecessary but I don't feel confident enough to optimize.

Closes #2411

[gaborbernat]

Who this does waaaay to much change, that I'm not comfortable with. We should only make it as much as possible. Also did you see how does the venv module handles this and why is not an issue there?

[pawelszramowski]

Did you notice that except for removing the first @echo off lines all the other changes are just adding a single @ before each command? echo off turns echo off for the current cmd.exe instance, @ turns it off for one line. @echo off is convenient and clean but there's no reasonable way to restore the caller's setting when you're done (yeah, batch is crap):

• https://stackoverflow.com/questions/9592732/restore-the-previous-echo-status
• https://stackoverflow.com/questions/48420074/was-echo-on-or-off-when-my-windows-bat-was-called

venv has got the same issue.

[pfmoore]

I can confirm, while this is pretty messy it is indeed the best way of doing this.

[gaborbernat]

Can you please fill in a similar PR for venv? thanks!