implement collision detection

• Collisions between bullet and terrain
• Collosions between bullet and tank

changed milestone to %Sprint 1: Basic functionality

added 💡 area::logic 🛠 Working on labels

assigned to @elifjoh

created branch 48-implement-collision-detection to address this issue

mentioned in merge request !55 (merged)

mentioned in commit 1ed6c774

closed with merge request !55 (merged)