bip62, mostly.

check_minimal_int: new.
make_push_str: use OP_0..OP_16, OP_1NEGATE.
new ScriptErrors: StackOverflow, NonMinimalPush, NonMinimalInt.
parse: when parsing, we have to remember what kind of push, so we can accurately unparse.
is_minimal: new.
check_minimal_push: new.
unparse_push: new
unparse_script: new 'minimal' arg.
various script checks.

render_int, unrender_int, make_push_str: don't shadow the cython versions.
make_push_int: use OP_1NEGATE.
walk_script: generator that flattens a parsed script (for op counting).
lo32: off by one.
machine:
  debug,strict,low_s,minimal - new flags.
  clear_stack: new.
  push_int: use push.
  pop_int: maybe check_minimal_int.
verifying_machine:
  check_sig: unparse script back to its original.
  check_multi_sig: npub & nsig checks.
  strict_der: DER checks.
  check_script0: new.
  check_script1: new.
  eval_script: call script checks.
  _eval_script:
    check_minimal_push.
    check stack depths.
verifying_machine_p2sh:
  script checks.
  check_p2sh: only pushes.
do_not: must use pop_int.
toplevel: do not put disabled opcodes in the map.
timeout idle connections.  seed an empty cache.
mostly bip62.

handle STRICTENC,MINIMALDATA flags.
__main__: args to ease testing of individual fails.