Many fixes and little improvements

Hello,
I came accross your script from [la-vache-libre.org](http://la-vache-libre.org/linkit-un-script-bash-pour-faciliter-la-creation-et-lintegration-de-lanceurs-dans-les-menus-de-vos-environnements-de-bureau-gnulinux/), and I gave it a try.

But I found quickly that there was numerous typos in the README and in the script itself, some grammar mistakes too. And it was not easily readable, and the indentation was mixed and sometimes broken.
bdd1445 fixes what I found necessary. You might not like some changes I made on the comments presentation, but I feel it is more clear now. Anyway, it's up to you to revert some things.
`dato` was changed to `cmd` and `namo` to `name`, among other things.

In bash, when a variable holds a filename, some problems can be encountered if the filename countains special characters such as spaces. Thats why escaping `$name` with double quotes is necessary. See 2ff70a5.

You also left a test to a Scrivania folder. This seems totally irrelevant, maybe something you left there from a previous test ? 657db59 fix this and concatenates the tests.

Finally, I added with bfa761b a small test to detect if `setup.sh` was run by root, if not it will stop the install process.

In the hope you'll find this useful and merge it into your project !