Reverting and reupdating it_IT with spelling and grammar corrections.

I'm reverting the last pull due to many spelling errors.
i've reimplemented the changes and updates here https://github.com/Azanor/thaumcraft/pull/1280 while fixing some spelling errors.
i've also reimplemented the rightful changes from the reverted pull... it was easier this way :D

I've decided against changing anything that could be controversial EXCEPT changing a couple of things for clarity and making all istances of "flusso" as in "Flux" back to "flux" due to the reasons listed in the commit.

If there's something wrong with the pull please let me know. It's my first, i might be doing it WRONG!!!!ONE!!!!

To the italians out there, @TheVikingWarrior  / @Walkersneps it's not meant as an offence. I just had some spare time and saw a couple of issues/the missed update request. If you find anything wrong please go ahead and comment/fix

Edit: Also, i've not changed "tronco" to "cassa", even if "tronco" is really really really hurting my eyes