Merge branch 'master' into generate-headers

doc/tutorial.rst

loopy/codegen/bounds.py

loopy/codegen/loop.py

loopy/isl_helpers.py

loopy/preprocess.py

loopy/symbolic.py

loopy/target/c/__init__.py

loopy/target/c/codegen/expression.py

loopy/target/ispc.py

loopy/target/python.py

loopy/transform/iname.py

test/test_apps.py

test/test_isl.py

test/test_loopy.py

test/test_reduction.py