Pass non-primitive types to C as 'borrowed' where appropriate

Parameters passed to C functions are considered to be owned by the
receiving function. As such, the receiving function must decrement the
parameter's reference count to avoid memory leaks.

An alternative is to pass parameters as borrowed by using the `@&`
prefix in their type. The receiving function does not need to decrement
the parameter's reference count but it must only be passed to other
non-consuming functions.

lean/Raylean/Core.lean

@@ -23,7 +23,7 @@ opaque disableCursor : IO Unit
 /- Drawing-related functions -/
 
 @[extern "clearBackground"]
-opaque clearBackground : (c : Color) → IO Unit
+opaque clearBackground : (c : @& Color) → IO Unit
 
 @[extern "beginDrawing"]
 opaque beginDrawing : IO Unit
@@ -32,13 +32,13 @@ opaque beginDrawing : IO Unit
 opaque endDrawing : IO Unit
 
 @[extern "beginMode2D"]
-opaque beginMode2D : (camera : Camera2D) → IO Unit
+opaque beginMode2D : (camera : @& Camera2D) → IO Unit
 
 @[extern "endMode2D"]
 opaque endMode2D : IO Unit
 
 @[extern "beginMode3D"]
-opaque beginMode3D : (camera : Camera3D) → IO Unit
+opaque beginMode3D : (camera : @& Camera3D) → IO Unit
 
 @[extern "endMode3D"]
 opaque endMode3D : IO Unit
@@ -80,40 +80,40 @@ opaque updateCamera : (camera : Camera3D) → (mode : CameraMode) → IO Camera3
 /- Basic shapes drawing functions -/
 
 @[extern "drawCircleV"]
-opaque drawCircleV : (center : Vector2) → (radius : Float) → (color : Color) → IO Unit
+opaque drawCircleV : (center : @& Vector2) → (radius : Float) → (color : @& Color) → IO Unit
 
 @[extern "drawLineV"]
-opaque drawLineV : (startPos : Vector2) → (endPos : Vector2) → (color : Color) → IO Unit
+opaque drawLineV : (startPos : @& Vector2) → (endPos : @& Vector2) → (color : @& Color) → IO Unit
 
 @[extern "drawRectangleRec"]
-opaque drawRectangleRec : (rectangle : Rectangle) → (color : Color) → IO Unit
+opaque drawRectangleRec : (rectangle : @& Rectangle) → (color : @& Color) → IO Unit
 
 /- Basic shapes collision detection functions -/
 
 @[extern "checkCollisionPointRec"]
-opaque checkCollisionPointRec : (point : Vector2) → (rect : Rectangle) -> IO Bool
+opaque checkCollisionPointRec : (point : @& Vector2) → (rect : @& Rectangle) -> IO Bool
 
 /- Screen-space-related functions -/
 
 /-- Get the world space position for a 2d camera screen space position -/
 @[extern "getScreenToWorld2D"]
-opaque getScreenToWorld2D : (position : Vector2) → (camera : Camera2D) → Vector2
+opaque getScreenToWorld2D : (position : @& Vector2) → (camera : @& Camera2D) → Vector2
 
 /- Text drawing functions -/
 
 @[extern "drawFPS"]
 opaque drawFPS : (posX : Nat) → (posY : Nat) → IO Unit
 
 @[extern "drawText"]
-opaque drawText : (text : @& String) → (posX : Nat) → (posY : Nat) → (fontSize : Nat) → (color : Color) → IO Unit
+opaque drawText : (text : @& String) → (posX : Nat) → (posY : Nat) → (fontSize : Nat) → (color : @& Color) → IO Unit
 
 /- Basic geometric 3D shapes drawing functions -/
 
 @[extern "drawCube"]
-opaque drawCube : (position : Vector3) → (width : Float) → (height : Float) → (length : Float) → (color : Color) -> IO Unit
+opaque drawCube : (position : @& Vector3) → (width : Float) → (height : Float) → (length : Float) → (color : @& Color) -> IO Unit
 
 @[extern "drawCubeWires"]
-opaque drawCubeWires : (position : Vector3) → (width : Float) → (height : Float) → (length : Float) → (color : Color) -> IO Unit
+opaque drawCubeWires : (position : @& Vector3) → (width : Float) → (height : Float) → (length : Float) → (color : @& Color) -> IO Unit
 
 @[extern "drawGrid"]
 opaque drawGrid : (slices : Nat) → (spacing : Float) → IO Unit
@@ -125,7 +125,7 @@ opaque loadImage : (resourceName : @& String) -> IO Image
 opaque loadTextureFromImage : (image : @& Image) -> IO Texture2D
 
 @[extern "drawTexture"]
-opaque drawTexture : (texture : @& Texture2D) -> (posX : Nat) -> (posY : Nat) -> (color : Color) -> IO Unit
+opaque drawTexture : (texture : @& Texture2D) -> (posX : Nat) -> (posY : Nat) -> (color : @& Color) -> IO Unit
 
 /--
 Source rectangle (part of the texture to use for drawing)
@@ -135,4 +135,4 @@ origin defines the point of the texture used as reference for rotation and scali
 rotation defines the texture rotation (using origin as rotation point)
 -/
 @[extern "drawTexturePro"]
-opaque drawTexturePro : (texture : @& Texture2D) -> (source : Rectangle) -> (dest : Rectangle) -> (origin : Vector2) -> (rotation : Float) -> (tint : Color) -> IO Unit
+opaque drawTexturePro : (texture : @& Texture2D) -> (source : @& Rectangle) -> (dest : @& Rectangle) -> (origin : @& Vector2) -> (rotation : Float) -> (tint : @& Color) -> IO Unit