DEV Proof Of Concept of 3-state game

To test: http://localhost:3000/dev

This proof of concept proves that 3-state game is doable

Following things needs to be done that 3-state can be used actually

Make very simple modes:
- Mainmenu: Add button which starts strategy or combat
- Combat: When you win/lose, automatically start strategy
- Strategy: Button to start combat

Refactor:
- Move old erisgame.js to combat.js

Improve:
- Every time new mode is called, Mainmenu/combat/strategy class-object is recreated. Should this be created once in game.init and be held within game-object?

Test:
- If we change modes like 100 times, will there be memory leaks?
Merge branch 'development' into two-state-game