Hefty Trash Can Lid lock

Remix of the hefty trash can lid lock. The geometry of the one I found was decent, but needed a few modifications. Mine is a very tight fit and almost impossible to remove without breaking it, but once it is on, it feels very secure and slides very well.

- Added a finger hold to make it easier to open.
- Moved the support triangles closer together so they don't interfere with the mechanism on the trash can.
- Reinforced the tabs that hold the lock onto the trashcan so they do not break off when installing.
- Slightly modified the profile on the rounded corners so they don't interfere with the lid.
- Shortened the parts that catch on the lid that keeps it in the open or closed position. They were too long and were making it very hard to move.