Provides an event called on_research_queue_changed that is raised at any change of research queue.
It is ment to replace on_research_cancelled, on_research_finished and on_research_started.
It uses almost the same interface as on_research_cancelled.

How to use:

• In your mod, add a dependency to this mod.
• In your control.lua add a function like this:
  local function InitialiseOnResearchQueueChanged()
defines.events.on_research_queue_changed = remote.call("on_research_queue_changed", "get_event_name")
script.on_event(defines.events.on_research_queue_changed, function (event) ... end)
end
• call this function in the on_init handler and in the on_configuration_changed handler
• The event structure is almost exactly like that of on_research_cancelled. The only difference is that the numbers for each technology are
  => -1 for cancelled,
  => 0 for completed and
  => 1 for started research.

Remark:

• Since the mod monitors the research queue with some latency, it may not detect all changes. For example, if another mod manipulates the research queue directly and adds and removes a technology between two checks, this will not be detected in on_research_queue_changed.