Move the C toolchain support to its own system cffi-toolchain.

Create linkable object files and include them in output-files for
compile-op, so that they can be found and linked by a recent-enough
ASDF (3.1.6 or later).

Allow for delivery of a system with a single static and/or dynamic
library, and on support platform (CLISP, CMUCL, SBCL), enable delivery
of a standalone executable that statically links required extensions.

This requires a recent SBCL (will hopefully be released in 1.2.17).
ASDF 3.1.6 is required, but backward compatibility code is
provided at least back to ASDF 3.1.2.

On BSD, use ld -r for "libraries" instead of ar and possibly libtool.

When forking a Lisp to dump an image, support Quicklisp.

Make CFFI-Grovel generally more robust.

Document static linking operations in manual. Improve documentation.

Add test for ASDF support including wrappers.

- Fix :LICENSE -> :LICENCE in cffi-grovel.asd
- grovel.lisp fixes:
    * fix OpenMCL's INVOKE
    * have INVOKE call NATIVE-NAMESTRING
    * add IGNORABLE declaration to DEFINE-GROVEL-SYNTAX
- CMUCL's EXT:UNIX-NAMESTRING is buggy, don't use it.
- strings.lisp: pass missing max-octets argument to OCTET-COUNTER
  in FOREIGN-STRING-ALLOC.

Added a groveller based on Dan Knap's and Matthew Backes's cffi-grovel
and Stelian Ionescu's fork iolib-grovel.  cffi-grovel is inspired by
SBCL's groveller.  This is a preliminary version.

Includes a new wrapper generator syntax to simplify the writing of
C glue libraries among other minor features.

- Updated TODO items related to grovelling.
- Integrated documentation into the CFFI manual.
- src/libraries: use ".so" as the default library suffix.