ada-mode no longer supports a different

ada-mode no longer supports a different
project file per buffer.  This was too complex.  Instead, there is now
a single active project file at any given time, and the user can switch
the active one through the Ada menu.  This revision also provides
better handling of the Windows command line, and the various available
shells on that platform.  ada-mode is now fully integrated with the GNU
visual debugger gvd, see http://libre.act-europe.fr.
(ada-prj-default-comp-opt): Use the new GNAT switch -gnatQ.  This is only
available with GNAT 3.14.
(ada-prj-gnatfind-switches, ada-cd-command): New variable.
(ada-quote-cmd): New function.
(ada-initialize-runtime-library): Get the location of the actual
runtime the compiler will be using, including support for
cross-platform environments.
(ada-treat-cmd-string): Add support for the new variable
${full_current} add support for debug-pre-cmd and debug-post-cmd, two
commands to run just prior to running the debugger, and just after
starting it.  This provide better support for cross-platform and
remote debugging.
(ada-get-absolute-dir): Remove, replace with expand-file-name.
(ada-gdb-application): New parameter executable-name.
(ada-get-ali-file-name): Better handling of separate packages.
Checkin on behalf of the ada-mode maintainer.