Fix typos throughout codebase.

* NEWS:
* README:
* doc/r5rs/r5rs.texi:
* doc/ref/api-data.texi:
* doc/ref/api-debug.texi:
* doc/ref/api-evaluation.texi:
* doc/ref/api-io.texi:
* doc/ref/api-macros.texi:
* doc/ref/api-procedures.texi:
* doc/ref/api-scheduling.texi:
* doc/ref/api-undocumented.texi:
* doc/ref/libguile-concepts.texi:
* doc/ref/posix.texi:
* doc/ref/srfi-modules.texi:
* doc/ref/vm.texi:
* doc/ref/web.texi:
* examples/box-dynamic-module/box.c:
* examples/box-dynamic/box.c:
* examples/box-module/box.c:
* examples/box/box.c:
* examples/safe/safe:
* examples/scripts/README:
* examples/scripts/hello:
* gc-benchmarks/larceny/twobit-input-long.sch:
* gc-benchmarks/larceny/twobit-smaller.sch:
* gc-benchmarks/larceny/twobit.sch:
* libguile/expand.c:
* libguile/load.c:
* libguile/net_db.c:
* libguile/scmsigs.c:
* libguile/srfi-14.c:
* libguile/threads.c:
* meta/guile.m4:
* module/ice-9/match.upstream.scm:
* module/ice-9/ports.scm:
* module/language/cps/graphs.scm:
* module/scripts/doc-snarf.scm:
* module/srfi/srfi-19.scm:
* module/system/repl/command.scm:
* test-suite/tests/srfi-18.test:
Fix typos.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

examples/scripts/README

@@ -14,7 +14,7 @@ installed and available with the standard installation prefix
 
 ** simple-hello.scm
 
-  The simplest "Hello World!" program for Guile. Run it like this:
+  The simplest "Hello World!" program for Guile.  Run it like this:
 
   $ guile -s simple-hello.scm
 

examples/scripts/hello

@@ -5,7 +5,7 @@
 ;;; This is the famous Hello-World-program, written for Guile.  It is a
 ;;; little bit enhanced in that it understands the command line options
 ;;; `--help' (-h) and `--version' (-v), which print a short usage
-;;; decription or version information, respectively.
+;;; description or version information, respectively.
 
 ;;; Author: Martin Grabmueller
 ;;; Date: 2001-05-29