reformat some code
prevent absolute cimports from trying relative imports
fix "from . cimport xyz" without package or module name in the "from" part
fix compiler crash during type inference of indexed ctuples
fix error message format in ctuple utility code
avoid accidental utility code generation for ctuple types
minor code cleanup
fix unused error handling code
minor code cleanup
clean up C tuple assignment unrolling code
add cythonize([Extension]) build test with additional source files
clean up some code and generate LetRefNodes in expected order for assignment unrolling
make item types of tuple/array unpacking inferable and institutionalise the IndexNode creation for the inference
tighten test assertions to make sure we correctly infer the target type during C array unpacking
be a bit smarter about the item index during type inference of indexed slices to allow for better type inference of non-homogeneous containers
fix type inference for starred assignments
extend array assignment test to include unpacking and starred assignments (even though it's currently highly inefficient)
guard against unknown index when inferring indexed item type
fix crash with starred assignments where IndexNode generated for type inference ended up being visited
drop C array unpacking back into C instead of going back and forth through Python list coercion