Move closed issues into a separate directory instead of deleting them.

Hi. I think it's much better for close command to actually move the closed issue into issues/closed directory instead of deleting them, for future reference in case the same issue occurs again.

[grantbow]

I've added a total of 845 commits to driusan/bug, first at grantbow/bug then over at grantbow/fit. I've made the close command configurable using options along with 20 other options to change the behavior of the program. One of them is CloseMove: true. Another is ClosePreventDelete: true. The directory can be closed or any other string by changing FitClosedDirName: closed. Defaults have been made identical to bug so far but may be changed in the future. Please let me know what you think.

@grantbow Awesome work!! 😃

[grantbow]

Thank you very much. I've been extending bug and implementing what I've needed. This includes some import (soon export and synch) capabilities with other bug tracking systems.