Fixing multicore for Powheg in master

This should fix the problem in PowhegControl noticed by @jkretz when running in multicore mode in master. I replaced the use of filter() python function in a couple of place. I also noticed that the use of binary i/o was causing some trouble, so I removed this since it doesn't seem necessary for writing things in the lhe files or in the logfiles.

I'm leaving this as Draft at the moment so that @jkretz can have a look.

For the sake of consistency I make (almost) the same changes in !52041 (closed) for 21.6.

Edited by Timothee Theveneaux-Pelzer

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