Merge remote-tracking branch 'origin/stable-2.0'

Moved scm_i_struct_hash from struct.c to hash.c and made it static.

The port's alist is now a field of 'scm_t_port'.

Conflicts:
	libguile/arrays.c
	libguile/hash.c
	libguile/ports.c
	libguile/print.h
	libguile/read.c

libguile/ports.h

@@ -132,6 +132,10 @@ typedef struct
   scm_t_port_encoding_mode encoding_mode;
   scm_t_string_failed_conversion_handler ilseq_handler;
   scm_t_iconv_descriptors *iconv_descriptors;
+
+  /* an alist for storing additional information
+     (e.g. used to store per-port read options) */
+  SCM alist;
 } scm_t_port;