Reimplemented Pathfinder to use A* instead of spawning an entity

#closes 788

features/pathfinder/find_vector.lua

@@ -0,0 +1,52 @@
+
+local FindVector = {}
+FindVector.__index = FindVector
+
+local function newFindVector( x, y )
+    return setmetatable( { x = x or 0, y = y or 0 }, FindVector )
+end
+
+function FindVector.__unm( vTbl )
+    return newFindVector( -vTbl.x, -vTbl.y )
+end
+
+function FindVector.__add( a, b )
+    return newFindVector( a.x + b.x, a.y + b.y )
+end
+
+function FindVector.__sub( a, b )
+    return newFindVector( a.x - b.x, a.y - b.y )
+end
+
+function FindVector.__mul( a, b )
+    if type( a ) == "number" then
+        return newFindVector( a * b.x, a * b.y )
+    elseif type( b ) == "number" then
+        return newFindVector( a.x * b, a.y * b )
+    else
+        return newFindVector( a.x * b.x, a.y * b.y )
+    end
+end
+
+function FindVector.__div( a, b )
+    return newFindVector( a.x / b, a.y / b )
+end
+
+function FindVector.__eq( a, b )
+    return a.x == b.x and a.y == b.y
+end
+
+function FindVector:__tostring()
+    return "(" .. self.x .. ", " .. self.y .. ")"
+end
+
+function FindVector:ID()
+    if self._ID == nil then
+        local x, y = self.x, self.y
+        self._ID = 0.5 * ( ( x + y ) * ( x + y + 1 ) + y )
+    end
+
+    return self._ID
+end
+
+return setmetatable( FindVector, { __call = function( _, ... ) return newFindVector( ... ) end } )