UI: add track_entity helper
Adds a couple small TODO comments (1000th commit!)
UI: update component gfx before overwriting entites

Resolves a small but noticible bug where:
- user visits site anon
- clicks on a system
- logs in
- moves an entity

Logging in will refresh / retrieve the user owned
entities from the server overwriting those previously
received when user was anon. The new entities will
_not_ have any graphical components though.

Once the entity moved, the movement callback triggered
a scene reload which attempted to remove the entity's
components from the scene before readding (during which
the entity components are initialized if they haven't
been yet). Thus two sets of entities appeared, those
not removed from the scene but no longer referenced
by the entity and those associated w/ the updated entity.

This patch resolves this by making sure locally initialized
gfx properties are copied over / preserved on updates.

Also contains a small fix hiding the entity container
on scene changes.