string.c:string_to_num

[Leopold Toetsch]

1) I've serious troubles with the precision of string_to_num. The test 
bewow fails, 1.e100 isn't really 10**100.
2) I've modified string_to_num to just use atof() which works.
3) This makes 2 tests fail (pmc_22, pmc_32). *But* these seem both to be 
bogus: I can't imagine that e.g. "Z1" should evaluate to int(1).

Can people please have a look at the implementation of string_to_num and 
at these tests.

Thanks,
leo
   new P9, .PerlNum
   pow N1, 10, 100
   set P9, N1
   new P10, .PerlNum
   set P10, 1.e100
   eq P9, P10, ok
   print "not "
ok:
   print "ok\n"
   end