PrepareWorld step takes too long on headless

[keturn]

loadProcesses.PrepareWorld currently documents itself as "loops until world is pre-generated or 5 second elapsed," and it's good to its word:

Terasology/engine/src/main/java/org/terasology/engine/core/modes/loadProcesses/PrepareWorld.java

Lines 32 to 38 in 2d0c434

	public boolean step() {
	if (worldRenderer.pregenerateChunks()) {
	return true;
	}
	EngineTime time = (EngineTime) context.get(Time.class);
	timeElapsed = time.getRealTimeInMs() - startTime;
	return timeElapsed > 5000;

The problem is that the HeadlessWorldRenderer looks like this:

Terasology/engine/src/main/java/org/terasology/engine/core/subsystem/headless/renderer/HeadlessWorldRenderer.java

Lines 124 to 126 in b27c8e2

	public boolean pregenerateChunks() {
	// TODO Auto-generated method stub
	return false;

so that loading step always takes five seconds in headless, no matter how much or how little time it takes to generate chunks.

This goes a long way to explaining why even the simplest possible MTE test always takes at least five seconds.

[keturn]

I wouldn't try to tackle this before finishing #4798.

I already tried the simple thing of changing the return false to a return true, and while the first MTE test in the run was fine, the next one had problems.