Merge remote-tracking branch 'upstream/master'

.gitlab-ci.yml

doc/ref_kernel.rst

doc/tutorial.rst

loopy/check.py

loopy/codegen/__init__.py

loopy/codegen/instruction.py

loopy/codegen/loop.py

loopy/isl_helpers.py

loopy/kernel/__init__.py

loopy/kernel/creation.py

loopy/kernel/data.py

loopy/kernel/instruction.py

loopy/kernel/tools.py

loopy/options.py

loopy/preprocess.py

loopy/schedule/__init__.py

loopy/symbolic.py

loopy/target/pyopencl_execution.py

loopy/tools.py

loopy/transform/batch.py