Solve Issue 624: minimap multiple selection tool

Adds a circle when you mouse over the minimap, beneath your cursor
-This circle is the effect range of your right click+mark
-Shift+scroll to change the size of this circle (ExodusMinimapAreaEffect)
-- Set the debug to 1 to have basically the same range as before (unless dots are stacked)
-This circle is also how many avatars are shown in the tooltip
-When this circle is over avatar dots, they change color (ExodusMapRolloverColor)
The menu functions still only work on the closest dot to your cursor on right click...
Thanks to Exodus for the majority of this code, the rest is my work and updates to be closer to LL in places.

indra/newview/llnetmap.h

@@ -132,6 +132,9 @@ private:
 	F32				mObjectMapTPM;			// texels per meter on map
 	F32				mObjectMapPixels;		// Width of object map in pixels
 	F32				mDotRadius;				// Size of avatar markers
+	// <exodus>
+	LLCachedControl<F32> mPickRadius;		// Size of the rightclick area of affect
+	// </exodus>
 
 	bool			mPanning;			// map is being dragged
 	LLVector2		mTargetPan;
@@ -148,8 +151,9 @@ private:
 	LLPointer<LLViewerTexture>	mParcelImagep;
 // [/SL:KB]
 
+	static std::map<LLUUID, LLVector3d> mClosestAgentsToCursor; // <exodus/>
+
 	LLUUID			mClosestAgentToCursor;
-	LLVector3d		mClosestAgentPosition;
 	LLUUID			mClosestAgentAtLastRightClick;
 
 	static void showAgentProfile(void*);