Merge pull request #27 from dsfb/master

Fix a few errors to build a release binary of the game and the map editor.

Update example gif file

Add missing pure virtual destructors with base implementations on interfaces

move cpp source code to cpp folder

Make pigs take damage on environment

Avoid raw pointers in the game characters

Avoid unnecessary calls to transition animation

Remove camera offset global

Add jump smoke animation

Update main character to Liv

Update README.md file

Update default level map

Add "Key" item

Ignore cmake-build-*/ folder