[PYTHON][TESTS][DOC] Various improvement of the API and code quality:

* Simplified `triton.kernel` API to achieve lower latency:
  > .data_ptr() must now be passed as kernel argument. No more implicit
conversion from torch.tensor
  > compilation options are now constant attributes, i.e., opt.d('VAR')
becomes opt.VAR
  > torch.device must now be passed explicitly to triton.kernel (no
longer inferred from torch.tensor arguments)
* C++ tests moved to `python/tests/`
* C++ tutorial created in `tutorials/`
* Python tutorial created in python/tutorials/
* Version changed to 1.0alpha
* No longer copying C++ headers into the Python package
* added python/triton/ops/ package for pre-written Triton ops

python/tests/test_softmax.py

@@ -0,0 +1,8 @@
+import torch
+import triton
+
+def test_op(M = 1024, N = 1024, dtype = torch.float32):
+    x = torch.randn(M, N, dtype=dtype, device='cuda')
+    th_y = torch.softmax(x, dim=-1)
+    tt_y = triton.ops.softmax(x)
+    assert torch.allclose(tt_y, th_y)