Const in more places! SMASH THE STATE.
Refactor, muteable stack.

- Added a muteable stack because rehash modifies the things it pops off
  of the stack
- Refactored unjar to use a generic 'retrieve' method that I can now use
  in cursor land.
Don't get it. Taking a break.
OH LOOk, THE PARENTHESES MATTEr. FUCK C.
Merge pull request #129 from infoforcefeed/cursor_helper_functions

Cursor helper functions