doc fixes

doc/index.rst

doc/ref_creation.rst

doc/ref_internals.rst

doc/ref_kernel.rst

doc/tutorial.rst

loopy/codegen/__init__.py

loopy/codegen/result.py

loopy/compiled.py

loopy/kernel/__init__.py

loopy/kernel/array.py

loopy/kernel/data.py

loopy/library/reduction.py

loopy/options.py

loopy/schedule/__init__.py

loopy/statistics.py

loopy/symbolic.py

loopy/target/__init__.py

loopy/target/c/__init__.py

loopy/target/c/codegen/expression.py

loopy/target/pyopencl_execution.py