Improve efficiency for constant values and various clean-ups.

[okamsn]

• Only evaluate values like :test and :by once.

• Add loopy--instr-let-var*, loopy--instr-let-const*, loopy--instr-let-var, loopy--instr-let-const. These macros are similar to macroexp-let2* in that the const versions try to pass constant values directly without creating a variable in the Loopy expansion.

  • Update array, array-ref, cons, list, list-ref, seq, seq-ref, seq-index, adjoin, union, nunion

  • Don't update numbers until after we remove the non-keyword args.

• Replace some uses of seq-let with cl-destructuring-bind.

• Use loopy--bind-main-body in some places.

• Add some TODOs.

• Fix list-ref tests to not modify literal constant list.

• Fix seq-ref tests to not modify literal constant list.

• Make loopy--find-start-by-end-dir-vals return the test function.

• Add :test to array, array-ref, sequence, sequence-index, and sequence-ref.

  • When going up on lists, use nthcdr instead of elt.

• Add sequence, sequence-ref, sequence-index, array, and array-ref tests for :downfrom and :upfrom as needed.