Changes to sprite animation system

* Changed the names of some of the functions
* Added functions for setting and returning the projection matrix of the active camera
* Added a function for getting the 2D screen coordinates from a 3D vector
* Added documentation for all the new functions

doc/files/translatesprite.txt

@@ -0,0 +1,8 @@
+#title TranslateSprite [RCBasic Doc]
+#header Sub TranslateSprite(sprite, x, y)
+
+Move a sprite relative to its current position
+
+Note: This function sets the position of a sprite without regards to physics properties so it will not trigger collision detection or collision response.
+
+#ref SetSpritePosition GetSpritePosition