Undo/Redo Commands for All Editor Functions

[dwjclark11]

Description
We currently only support Undo/Redo commands for the tilemap editor, we need to add this functionality for all aspects of the editor where we are changing/adding/remove something etc.

• Adding game objects
• Adding components to game objects
• Changing transforms or other component properties.
• etc.

Prerequisites

• The latest master repo.
• A project created for testing.

Expected behavior
Should be able to undo/redo more editor functionality.

Actual behavior
Only tilemap operations are handled.

[dwjclark11]

Just added the following commands:

• RemoveTileLayerCmd
  • When deleting a layer this happens:
    • Removes the layer.
    • Deletes all tiles at that layer.
    • Moves all layers above down one layer.
    • Moves all tile sprite layers above down one layer.
• AddTileLayerCmd
  • When adding a layer this happens:
    • Adds a new layer to the layer params in order.
    • The new layer is now the highest layer.
• MoveTileLayerCmd
  • When the tile layer is moved, this happens:
    • The layers are swapped.
    • The underlying layer numbers are changed.
    • The tile entity sprite layers are swapped.
• ChangeTileLayerNameCmd
  • When the name is changed, this happens:
    • Oldname is replaced with the new name if it does not already exist as a layer.

All commands have fully undo/redo functionality.

More commands to come.