Tunes GC scheduling a bit to reduce memory usage.

The main problem was that GC was only called from the simulation before
this patch. This means when you were waiting in the multiplayer lobby or
just had the GUI open, it only called GC when getting close to the JS
runtime size limit (I assume). Another problem was the Net Server
runtime which didn't GC either. Here the runtime size limit is 16 MB
though, so it's not too terrible. These issues have both been addressed
and GC has been given a bit more time per incremental slice to make sure
it gets done in time. It's still far from perfect, but there are too
many changes in SpiderMonkey related to GC, so I don't want to spend too
much time on this yet.

Refs #2808

This was SVN commit r15787.

source/scriptinterface/ScriptInterface.h

@@ -59,6 +59,7 @@ class AutoGCRooter;
 
 // TODO: what's a good default?
 #define DEFAULT_RUNTIME_SIZE 16 * 1024 * 1024
+#define DEFAULT_HEAP_GROWTH_BYTES_GCTRIGGER 2 * 1024 *1024
 
 struct ScriptInterface_impl;
 
@@ -89,7 +90,8 @@ public:
 	 * Each runtime should only ever be used on a single thread.
 	 * @param runtimeSize Maximum size in bytes of the new runtime
 	 */
-	static shared_ptr<ScriptRuntime> CreateRuntime(int runtimeSize = DEFAULT_RUNTIME_SIZE);
+	static shared_ptr<ScriptRuntime> CreateRuntime(int runtimeSize = DEFAULT_RUNTIME_SIZE, 
+		int heapGrowthBytesGCTrigger = DEFAULT_HEAP_GROWTH_BYTES_GCTRIGGER);
 
 
 	/**
@@ -354,10 +356,12 @@ public:
 	 * be worth the amount of time it would take. It does this with our own logic and NOT some predefined JSAPI logic because
 	 * such functionality currently isn't available out of the box.
 	 * It does incremental GC which means it will collect one slice each time it's called until the garbage collection is done.
-	 * This can and should be called quite regularly. It shouldn't cost much performance because it tries to run a GC only if 
-	 * necessary.
+	 * This can and should be called quite regularly. The delay parameter allows you to specify a minimum time since the last GC
+	 * in seconds (the delay should be a fraction of a second in most cases though). 
+	 * It will only start a new incremental GC or another GC slice if this time is exceeded. The user of this function is 
+	 * responsible for ensuring that GC can run with a small enough delay to get done with the work.
 	 */
-	void MaybeIncrementalRuntimeGC();
+	void MaybeIncrementalRuntimeGC(double delay);
 	
 	/**
 	 * Triggers a full non-incremental garbage collection immediately. That should only be required in special cases and normally