Add 'scm_i_from_double' and use it.

Add 'scm_i_from_double' and use it.

* libguile/numbers.c (scm_i_from_double): New static function.
  (scm_from_double): Just call 'scm_i_from_double'.
  (scm_inf, scm_nan, scm_abs, scm_i_inexact_floor_quotient,
  scm_i_inexact_floor_remainder, scm_i_inexact_floor_divide,
  scm_i_inexact_ceiling_quotient, scm_i_inexact_ceiling_remainder,
  scm_i_inexact_ceiling_divide, scm_i_inexact_truncate_quotient,
  scm_i_inexact_truncate_remainder, scm_i_inexact_truncate_divide,
  scm_i_inexact_centered_quotient, scm_i_inexact_centered_remainder,
  scm_i_inexact_centered_divide, scm_i_inexact_round_quotient,
  scm_i_inexact_round_remainder, scm_i_inexact_round_divide,
  scm_max, scm_min, scm_sum, scm_difference, scm_product,
  scm_divide, scm_truncate_number, scm_round_number, scm_floor,
  scm_ceiling, scm_expt, scm_sin, scm_cos, scm_tan, scm_sinh,
  scm_cosh, scm_tanh, scm_asin, scm_acos, scm_atan, scm_sys_asinh,
  scm_sys_acosh, scm_sys_atanh, scm_real_part, scm_imag_part,
  scm_magnitude, scm_angle, scm_exact_to_inexact, log_of_shifted_double,
  log_of_fraction, scm_log10, scm_exp, scm_sqrt, scm_init_numbers):
  Use 'scm_i_from_double' instead of 'scm_from_double'.