Now foreach_reverse with delegates has been deprecated.
Merge pull request #648 from quickfur/foreach_reverse_delegate

Now foreach_reverse with delegates has been deprecated.
Update variadic templates section

Use clearer names for variadic auto ref arguments.
Move tuple length and slicing details before example using length.
Update curry example -> partial and simplify by returning a closure.
Merge pull request #639 from ntrel/patch-2

Improve variadic templates section