message: Fix links to OpenGL API in docs
  Those links were broken before, since the [] and () part were split
  into two different lines. This also caused warnings on nightly, which
  are now fixed.
diff: @@ -24,8 +24,9 @@ use num::BaseFloat;
  /// Create a perspective projection matrix.
  ///
  -/// This is the equivalent to the [gluPerspective]
  -/// (http://www.opengl.org/sdk/docs/man2/xhtml/gluPerspective.xml) function.
  +/// This is the equivalent to the [`gluPerspective`] function.
  +///
  +/// [`gluPerspective`]: https://www.opengl.org/sdk/docs/man2/xhtml/gluPerspective.xml
  pub fn perspective<S: BaseFloat, A: Into<Rad<S>>>(
  fovy: A,
  aspect: S,
  @@ -42,8 +43,9 @@ pub fn perspective<S: BaseFloat, A: Into<Rad<S>>>(
  /// Create a perspective matrix from a view frustum.
  ///
  -/// This is the equivalent of the now deprecated [glFrustum]
  -/// (http://www.opengl.org/sdk/docs/man2/xhtml/glFrustum.xml) function.
  +/// This is the equivalent of the now deprecated [`glFrustum`] function.
  +///
  +/// [`glFrustum`]: http://www.opengl.org/sdk/docs/man2/xhtml/glFrustum.xml
  pub fn frustum<S: BaseFloat>(left: S, right: S, bottom: S, top: S, near: S, far: S) -> Matrix4<S> {
  Perspective {
  left: left,
  @@ -57,8 +59,9 @@ pub fn frustum<S: BaseFloat>(left: S, right: S, bottom: S, top: S, near: S, far:
  /// Create an orthographic projection matrix.
  ///
  -/// This is the equivalent of the now deprecated [glOrtho]
  -/// (http://www.opengl.org/sdk/docs/man2/xhtml/glOrtho.xml) function.
  +/// This is the equivalent of the now deprecated [`glOrtho`] function.
  +///
  +/// [`glOrtho`]: http://www.opengl.org/sdk/docs/man2/xhtml/glOrtho.xml
  pub fn ortho<S: BaseFloat>(left: S, right: S, bottom: S, top: S, near: S, far: S) -> Matrix4<S> {
  Ortho {
  left: left,
  