Description:

Save 4 component initializations per entity.

Allows for setting with object3D API on creation without the component overriding with 0/0/0:

var entity = document.createElement('a-entity');
entity.object3D.position.set(1, 2, 3);
scene.appendChild(entity);

Changes proposed:

• Save 4 component initializations per entity.
• Don't need pos/rot/scale/vis components initializations by default if not defined.
• Removes a bunch of code in the component lifecycle that checks for default component