Added first UI elements

Rules can be created from the UI
Game can be stopped/started from the UI
Current level can be reset (Load from file again)
Added "Game" target and main file

TODO (A lot):
 - Unit tests
 - Fully functionnal UI
 - Win conditions
 - Level background
 - Level switching/progression
 - Interesting and varied rules
 - Multi-scale pathfinding
 - etc

README.md

@@ -33,18 +33,19 @@ The class diagram omits most constructors and getters.
  - [ ] Rules
   - [x] Creation
   - [x] Interaction with entities
-  - [ ] Parsing of rules and creation of subsequent decorators
+  - [x] Parsing of rules and creation of subsequent decorators
   - [x] Find optimal target for pathfinding
   - [ ] Other rules (Waiting...)
  - [ ] Graphics
   - [x] Scene rendering
+  - [x] Some kind of UI
   - [ ] UI
   - [ ] Menu ?
  - [ ] Gameloop
-  - [ ] Transition from starting to running state and vice-versa
-  - [ ] Entity behaviour evolution
+  - [x] Transition from starting to running state and vice-versa
+  - [x] Entity behaviour evolution
   - [x] Rule application
   - [ ] Win condition
   - [ ] ~~Saving state through serialization ?~~
- - [ ] UML
+ - [x] UML
  - [ ] Unit tests