Encapsulate VAO/VBO in a new class, try to represent vertex formats as objects, factor out super class from BillboardList.
Rename BillboardList to BulletEmitter
Use parent type when referring to players bullet emitter.
Rename billboard/ directory to bullet/, reflecting whats actually in there.
Fix bug where new code not being used
Fix bug with attributes not being used and factor out particle storage to specific types.
Add billboard particles for an explosion effect. BREAKING CHANGE. Still a WIP.