UI: bind context of http_invoke call in station construction

Previously the Node#http_invoke was being invoked in an unbound
context, regression slipped in during refactoring
UI: fix JumpGateParticles#clone parameter list

Small regression introduced during refactoring
UI: add jg selection & lamp to mesh instead of scene

Simplifies/optimizes some operations since gfx components
are now related to each other and do not have to be tracked
independently.
UI: tweak lamp effect to remove conditional
UI: add TODO comment