Added stepped ranges
Created by: drosseau
Half of #457 (closed)
Syntax is now:
{1..2...7}
-> 1 3 5 7
{1..2..7}
-> 1 3 5
{a..2...e}
-> a c e
{a..2..e}
-> a c
and similarly for backwards and negatives.
Also added some tests to the examples dir.
(I'm not sure why those two earlier commits are in this.. I let my repo get messed up somehow)