Move array reader from arrays.c to read.c

Move array reader from arrays.c to read.c

* libguile/arrays.c (read_decimal_integer): Move to read.c.
  (scm_i_read_array): Remove.  Incorporate the code into the
  'scm_read_array' static function in read.c.

* libguile/arrays.h (scm_i_read_array): Remove prototype.

* libguile/read.c (read_decimal_integer): Move here from read.c.
  (scm_read_array): Incorporate the code from 'scm_i_read_array'.  Call
  'scm_read_vector' and 'scm_read_sexp' instead of 'scm_read'.