Merge pull request #87 from bvssvni/master

Upgraded to latest Piston
block_state: fixup ao_face, not only cull_face, when rotating the model.
block_state: adjust expected "above" to match vertices rounded "down".
Differentiate between transparent-solid, opaque and transparent blocks, for AO.
Merge pull request #88 from eddyb/lighting-fixes

Lighting/AO improvements.
shader: store a batch in Buffer to avoid a linear lookup for each render call.
Display more debug information in the title, including timings.
Merge pull request #90 from eddyb/gfx-perf-and-counters

Removed a source of quadratic behavior and added some timings.
Update gfx-rs.
Merge pull request #91 from eddyb/update-gfx

Update gfx-rs.
minecraft: fix rotation over z axis

When a model (e.g. a torch on a wall) has a rotation over the z axis, we
were rotating the model the wrong way around.
Merge pull request #95 from carlosmn/z-rotation

minecraft: fix rotation over z axis
update readme with getting started and loading world
Merge pull request #97 from mkcp/master

update readme with getting started and loading world
Upgraded to latest Piston + Gfx