This reverts commit 0e9dd80f.

- adds outer inames to prefetches/precomputes to ensure all instructions
  are within all the hardware axes of the kernel.
- adds inames to instructions to ensure all instructions are within all
  the hardware axes of the kernel.

remove unused iname gi from test_tim2d and comment out duplicate_inames calls whose within id doesn't match anything

Allow lang version setting with LOOPY_KERNEL_LANGUAGE_VERSION global in make_kernel caller's global space

- Rename apply_subst to expand_subst.

- Track if precomputes in other substitution rules are uniformly
  in-footprint, and if so, perform substitution to storage reference
  even within substitution rules.

- Remove 'formal argument' sweep spec from precompute(). This is purely
  counterintuitive, because it finds an intermediate set of inames that
  then get swept out and thereby may pick up much more than the formal
  argument referenced.

- Fix the 'in-footprint' criterion to be the storage-to-sweep map with
  the sweep dimensions projected out.