Variable Size Regions! Support for prehash RegionSizeX and large patches. (WIP)

Mostly from Ukando, tweaked a bit to be cleaner, and a little less dramatic.

decode_patch_header now takes a bool optionally, as third argument.
_PREHASH_RegionSizeX is the only used of the two _PREHASH_RegionSize*.
llsurface.cpp: Copy the connectNeighbor for variable size regions almost directly from Ukando
llsurfacepatch.cpp: Patch code from ukando and voodoo.
Changed hardcoded 256 constants and such to width functions in: llglsandbox.cpp, llsurface.cpp, llviewerregion.cpp, llviewerparcelmanager, llviewerparcelmgr.cpp, llvowater.cpp, llworld.cpp
Use region specific width in: llagent.cpp, llglsandbox.cpp, llmanip.cpp, llmanipscale.cpp, llpanelobject.cpp, llviewerbject.cpp, llwind.cpp
Use 256 in llnetmap.cpp in places...
llfloaterregioninfo.cpp: Aurora grid has wacky textures.
Add LLViewerParcelMgr::widthUpdate() for updating mParcelsPerEdge given a region's width. Used in llstartup now.
Add LLWorld::setWidth() for getting a region's size from LLMessageSystem pointers and setting mWidth and mWidthInMeters, accordingly. Called in llviewermessage.cpp as well.

indra/newview/llworld.h

@@ -113,6 +113,10 @@ public:
 	LLSurfacePatch *		resolveLandPatchGlobal(const LLVector3d &position);
 	LLVector3				resolveLandNormalGlobal(const LLVector3d &position);		// absolute frame
 
+	// update region size
+	void					setRegionWidth(LLMessageSystem* msg);
+	void					setRegionWidth(const U32 width = 0);
+
 	U32						getRegionWidthInPoints() const	{ return mWidth; }
 	F32						getRegionScale() const			{ return mScale; }
 
@@ -177,12 +181,12 @@ private:
 	region_list_t	mCulledRegionList;
 
 	// Number of points on edge
-	static const U32 mWidth;
+	static U32 mWidth;
 
 	// meters/point, therefore mWidth * mScale = meters per edge
 	static const F32 mScale;
 
-	static const F32 mWidthInMeters;
+	static F32 mWidthInMeters;
 
 	F32 mLandFarClip;					// Far clip distance for land.
 	LLPatchVertexArray		mLandPatch;