Nested with statments & fixed up for/foreach

So, since making nested "with" statements too work was just a simple cut&paste from the "for" macro, the original with statement got a name change too "with*".

`with*` was chosen primarily because @paultag argued that naming it according too PEP8 (`with_`), would make other people break PEP8 too get the name right (did i get that right?). Therefor we settled on using the Clojure way of naming the built-in functions instead.

Now, since we had too do this, changing the for/foreach function&macro is a natural step following the while/while* naming convention.
Therefor i i also added those changes. This also means the "for" section of the docs is removed, and the foreach section got a rename.

I am awaiting the :fire:!

(This fixes the issue in https://github.com/hylang/hy/issues/285)

:shipit: