1.0.48.6: %SIMPLE-EVAL and backtraces

1.0.48.6: %SIMPLE-EVAL and backtraces

  Functions from %SIMPLE-EVAL have names such as (EVAL (DEFMACRO FOO)),
  which looks pretty confusing in the backtrace.

  Replace that with #:EVAL-THUNK, which is more descriptive and
  less head-scratchy.

  Also, calls to SIMPLE-EVAL-IN-LEXENV and EVAL -- when they show
  up in backtraces -- have lisp forms as arguments. This causes
  pretty-printing to try and split things onto multiple lines,
  but *PRINT-LINES* tends to be 1 during backtracing.

  ...so bind *PRINT-PRETTY* to NIL when printing eval-frame
  arguments iff *PRINT-LINES* is 1 in order to have something
  useful show up the backtrace.