Future Feature - Erasing your future

[aljachimiak]

Consider the following premise:

1. You have run fur init on a project
2. You have run fur store five times and your fur pointer is at 6
3. You run fur back three times to view an old version; your fur pointer is at 3
4. You make changes and decide to go in a new direction
5. You run fur store to save your changes; your fur pointer is a 4

This is where the problem lies
You have two more diffs in .fur/diffs/ called 4.f and 5.f that refer back to potentially non-existant lines, directories, or files.

Feature - Erase the future

At #5 in the situation above, fur store should do the following:

1. check to see if #{pointer}.f exists
2. prompt user: "You are about to destroy #{ #{number of .fur/diffs/} - 1 } future versions. Do you want to store your project and continue? [y/n]
3. if [y], continue with store; and:
   3.5. loop through the .fur/diffs directory and rm all i.f files that are greater than the #{new fur pointer}.
4. if [n]; Return a message: "Your changes have not been stored"