Document that we support srfi-87 and add it to %cond-expand-features.

* module/ice-9/boot-9.scm (%cond-expand-features): Add srfi-87.

* doc/ref/srfi-modules.texi (SRFI-0): Add srfi-87 to the list of core
  features.
  (SRFI-87): New node.
Document that we support srfi-46 and add it to %cond-expand-features.

* module/ice-9/boot-9.scm (%cond-expand-features): Add srfi-46.

* doc/ref/srfi-modules.texi (SRFI-0): Add srfi-46 to the list of core
  features.
  (SRFI-46): New node.

* doc/ref/api-macros.texi (Syntax Rules): Mention that the custom
  ellipsis identifier support is specified by SRFI-46.

* test-suite/tests/syntax.test ("syntax-rules"): Add ellipsis hygiene
  test from SRFI-46.
Custom binary input ports sanity-check the return value of 'read!'.

* libguile/r6rs-ports.c (cbip_fill_input): Throw an exception when
  C_OCTETS is greater than what was requested.
* test-suite/tests/r6rs-ports.test ("7.2.7 Input Ports")["custom binary
  input port 'read!' returns too much"]: New test.
web: Don't throw if a response is longer than its Content-Length says.

* module/web/response.scm (make-delimited-input-port): Read at most LEN
  bytes from PORT, instead of trying to read more and returning an error
  if more is available.  Try again when 'get-bytevector-n!' return zero.
* test-suite/tests/web-response.test (example-1): Add garbage after the
  body itself.
Arrange so that 'file-encoding' does not truncate the encoding name.

Fixes <http://bugs.gnu.org/16463>.
Reported by Sree Harsha Totakura <sreeharsha@totakura.in>.

* libguile/read.c (ENCODING_NAME_MAX_SIZE): New macro.
  (SCM_ENCODING_SEARCH_SIZE): Change to 500 + ENCODING_NAME_MAX_SIZE.
  (scm_i_scan_for_encoding): Return NULL if there's less than
  ENCODING_NAME_MAX_SIZE bytes once "coding: *" has been read.
* test-suite/tests/coding.test ("line
  comment")["http://bugs.gnu.org/16463"]: New test.
Thank Sree Harsha.
doc: embedding example more readable.

* doc/ref/guile.texi (A Sample Guile Main Program): Easier to read
  example code and building split into 2 subsections.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Fix (port-conversion-strategy #f).

Reported by Doug Evans <xdje42@gmail.com>.

* libguile/ports.c (scm_port_conversion_strategy): Don't validate
  that 'port' is an open port until after the (port == #f) case
  has been handled.
Merge branch 'stable-2.0'

Conflicts:
	libguile/read.c
	test-suite/tests/web-response.test