Rename gem, flip stack (2012)

[epitron]

• For conceptual coherence, show-stack was flipped, so that 'up' actually goes up and 'down' actually goes down.
• 'show-stack' command was renamed to 'stack', and 'show-stack' is now an alias to 'stack' (for backwards compatability)

[rking]

@banister likes the consistency with ruby-debugger and gdb, but agrees that a config option would be useful.

Also, at that point, it would be useful to have a special pager var just for showing the stack, so you could pipe it to less +G so you see the bottom frames right away. (And, also, you could prepend with grep -v RailsyStuff to trim it down, if you wanted)

[joallard]

This is really interesting from a design perspective!