* read.c (scm_lreadr): When reading a hash token, check for a

	* read.c (scm_lreadr): When reading a hash token, check for a
	user-defined hash procedure first, so that overriding the builtin
	hash characters is possible (this was needed for implementing
	SRFI-4's read synax `f32(...)').

	* num2integral.i.c: Use scm_t_signed_bits instead of scm_t_bits,
	because the latter is unsigned now and breaks comparisons like
	(n < (scm_t_signed_bits)MIN_VALUE).