Fix memory leaks

When using the product it is leaking memory.

The following kind of usage will be done in order to find memory leak.
After each group of steps is done close the app and check for leaks.

1. Most basic
- open the app
- close the app
2. shapes
- open the app
- insert a single shape (circle, rectangle, image, svg)
- close the app
3. keyframes
- open the app
- insert a rectangle
- add a new keyframe that will move the object along X axis
- move the object
- close the app
4. Any type of keyframes
- open the app
- insert a rectangle
- add a keyframe for each possible type of keyframe
- move the object to trigger all keyframes
- close the app
5. Any type of shapes
- open the app
- insert all kind of shapes
- add a keyframe to move it along a certain axis
- close the app
6. UndoStack
- open app
- insert a shape
- move it
- add keyframes
- delete keyframe
- deleteshape
- undo all actions
- close the app

might do it in multiple PRs.