Get magicleap working again

[asajeffrey]

These are the changes needed to get the magicleap demo running again. There are some minor changes to the common demo, the main one is calling make_current for each eye during rendering, previously we were assuming the only difference between eyes was the viewport.

[jdm]

error[E0432]: unresolved import `pathfinder_geometry::basic::point`
  --> demo/magicleap/src/lib.rs:32:33
   |
32 | use pathfinder_geometry::basic::point::Point2DF;
   |                                 ^^^^^ could not find `point` in `basic`
error[E0432]: unresolved import `pathfinder_geometry::basic::point`
  --> demo/magicleap/src/lib.rs:33:33
   |
33 | use pathfinder_geometry::basic::point::Point2DI;
   |                                 ^^^^^ could not find `point` in `basic`
error[E0432]: unresolved import `pathfinder_geometry::basic::point`
  --> demo/magicleap/src/magicleap.rs:51:33
   |
51 | use pathfinder_geometry::basic::point::Point2DI;
   |                                 ^^^^^ could not find `point` in `basic`
error[E0432]: unresolved import `pathfinder_geometry::basic::point`
  --> demo/magicleap/src/magicleap.rs:52:33
   |
52 | use pathfinder_geometry::basic::point::Point2DF;
   |                                 ^^^^^ could not find `point` in `basic`
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0432`.
error: Could not compile `pathfinder_magicleap_demo`.
To learn more, run the command again with --verbose.
The command "cargo build" exited with 101.

[pcwalton]

Looks good. I just removed cross, so the first commit can be removed.

[pcwalton]

@asajeffrey Point has been renamed to Vector. You can run something like sed s/::point/::vector/g and s/\bPoint(\d)D/Vector\1/g.